fig1 - 5 illustrate , in various levels of detail , the structure and operation of an electrical socket assembly which is used in the invention . the electrical socket assembly 10 includes an outer module 12 made of a flexible , elastic , nonconductive material , such as a natural or synthetic rubber . the module 12 essentially forms a bladder , or chamber , within which an electrical socket structure is disposed . an end seal 14 is formed in the module for sealing the back end of the module . an entry lip seal 16 is formed in the forward end of the module . the module 12 is essentially cylindrical in shape , with both of the seals 14 and 16 consisting of annular structures , each pierced through with a passageway opening into the module 12 . the material from which the module 12 is formed is elastic so that the seals 14 and 16 radially constrict against objects inserted into their respective passageways to form therewith respective barriers resistant to fluid and pressure . a dielectric fluid 18 fills the interior of the module 12 . the fluid 18 has the same characteristics as the fluid which fills the bladders of the inventor &# 39 ; s cited u . s . patents , and is used for the same purposes . a movable dielectric stopper 20 has a forward extension , or tip 21 , which extends through the passageway formed in the entry lip seal 16 . the stopper 20 is free to slide within the module 12 . the radially constrictive force exerted by the lip seal 16 through the passageway seals the lip seal 16 against the stopper tip 21 to form a fluid and pressure resistant barrier . the barrier prevents the transfer of fluid between the interior and exterior of the module 12 . with reference to fig4 and 5 , it will be evident that , as a probe 126 is inserted into the module 12 through the entry lip seal 16 , the probe will engage the end of the stopper tip 21 , pushing it into a retracted position within the module 12 . the probe 126 follows the stopper tip on its trip into the interior of the module 12 , thereby replacing the stopper tip 21 in the barrier formed with the entry lip seal 16 . when the probe is withdrawn , the stopper tip 21 follows the probe as it leaves the passageway in the entry lip seal 16 , and replaces the probe in the barrier formed with the lip seal 16 . one will appreciate that the mating and demating of a probe with the electrical socket assembly does not require expansion of the passageway in the lip seal 16 when the probe is inserted , nor contraction of the passageway when the probe is removed . since the stopper 20 eliminates the requirement for closing the entry lip seal 16 when the probe is withdrawn , the need for the constricting elements for the prior art bladder assemblies is eliminated , thereby reducing the insertion and extraction forces necessary for mating and demating the electrical socket assembly 10 with a probe . returning to fig1 and 2 , electrical conductivity is provided within the socket assembly 10 by a conductive rear piece 22 , a cylindrical conductive tube 24 , a conductive forward piece 26 , and an annular contact band 28 . each of the elements 22 , 24 , 26 , and 28 is made of an electrically conductive material . the rear piece 22 has an annular groove 23 for receiving and sealing to the inner end seal 14 of the module 12 , and a forward extension 25 which is received in one of the tube 24 . the tube 24 extends between the end piece 22 and the forward piece 26 , which fits into the forward end of the tube 24 . the forward piece 26 has a forward extension with an interior annular groove 27 in which the annular contact ring 28 is seated . electrical conductivity is thus provided from the forward end of the module 12 , out , through the rear end of the module . a stopper return spring 30 is disposed inside the tube 24 and acts between the forward end of the end piece 22 in the rear end of the stopper 20 . when a probe is inserted into the electrical socket assembly 10 and moves the stopper 20 rearwardly within the tube 24 , the dielectric fluid 18 is displaced somewhat by the rearward motion of the stopper . this results in a deformation of the module 12 . as shown in fig2 the fluid 18 is ported through radial holes 32 in the tube 24 . as shown most clearly in fig2 , and 5 , the stopper tip 21 engages the end of a probe by means of a concave face 34 in the end of the tip 21 . when the stopper 20 is pushed out of place by a probe , the probe enters the forward passageway through the entry lip 16 and engages the contact ring 28 to establish conductivity between the probe and the conduction apparatus in the socket assembly 10 . as the probe is inserted through the entry lip seal 16 , it pushes the stopper 20 rearwardly in the tube 24 , thereby compressing the spring 30 . the spring 30 is of such a dimension that the stopper 20 can be pressed into the tube 24 and will be recessed only to the point where the concave face 34 is displaced just to the rear of the annular contact ring 28 within the front piece 26 . the bore of the front piece 26 acts as a longitudinal guide for the stopper tip 21 , aligning it longitudingly with the passageway through the entry lip seal 16 . of course , when the probe is withdrawn from the passageway in the entry lip seal 16 , the spring 30 urges the stopper 20 forward into the breach : the stopper follows the probe , until the probe is completely withdrawn . the spring 30 then continues stopper 20 forward until the large cylindrical seat 50 engages the shoulder 48 of the forward piece 26 . the diameter of the cylindrical seat 50 is slightly less than the interior diameter of the tube 24 , so that the tube 24 acts as a guide to the seat 50 . as shown in fig2 , and 6 , the enlarged cylindrical seat 50 of the stopper 20 is slotted by slots 56 , to permit the fluid 18 to flow past the stopper 20 as the stopper is being displaced within the module 12 . as shown in fig1 and 2 , the end - piece 22 includes a pair of annular grooves 35 that provide seats for a pair of o - ring seals 36 . the end piece 22 has a tapered transition forming a load - bearing shoulder 40 , and a solder pot 42 bored in its furthest tip . a snap - ring 38 is seated in an annular groove 39 formed just forward of the shoulder pot 42 in the outer surface end piece 22 . in summary , then , the structure of the electrical socket assembly illustrated in fig1 - 6 , provides a protected environment for a contact surface ( the ring 28 ), which is entered through an end seal 16 . the stopper 20 ensures that the end seal 16 never has to close completely to a zero - diameter hole when a probe is withdrawn from it . the entry lip seal 16 acts against the stopper tip 21 and a male probe having a slightly larger diameter than the stopper tip . thus , the entry lip seal 16 is always full of something , either the stopper tip 21 , or a probe . there is never a requirement for the lip seal to substantially alter its dimensions . therefore , only a minimal amount of stretch of the material of the module 12 is required for cycling a probe . further , the entry lip seal 16 is a one - way seal in that it seals from the outside environment . thus , the fluid 18 can flow from inside the module 12 , which requires only enough internal high pressure to overcome the elasticity of the entry lip seal 16 . the module material is selected to be substantially elastic , the entry lip seal 16 is not leaky . however , in the event that additional constrictive elements are required to maintain the integrity of the entry lip seal 16 , one can appreciate that the insertion force required to move a probe into the seal 16 will still be substantially less with the arrangement illustrated in fig2 than if the probe were required to open the passageway through the seal from a zero diameter . one can contemplate an alternative embodiment of the entry lip seal 16 in the form of one or more o - rings disposed within the bore of the front piece 26 , forward of the contact ring 28 . the o - rings would be alternated with one or more annular dielectric pieces to seat the rings and to close the electrical path . since the electrical socket assembly 10 is intended to be disposed within a bladder assembly in a receptacle , described below , no significant pressure differential would exist across these o - ring , thereby facilitating the movement of the socket tip 21 past the rings . the integrity of the seal at the forward end of the electrical socket assembly 10 is enhanced by a conventional rubber - to - metal bond 46 , which can be assisted or replaced by an external clamping collar on the outside of the module 12 over the forward piece 26 . a small annular cavity 54 is formed in the forward portion of the module 12 between the rear of the entry lip seal 16 and the forward end of the end piece 26 . this is shown in fig2 , and 5 . the cavity prevents a conductive path forming between the forward conductive part 26 and the external environment . such a conductive path could be created by the small scratch through the lip seal caused by sand , or a burr , on a probe . under certain circumstances , such scratches might contain traces of sea water with an electrically - conductive composition . in order to prevent conduction under such circumstances , the cavity 54 is filled with a dielectric fluid , thereby providing a dielectric barrier . refer now to fig7 - 11 for an understanding of the second aspect of the invention . the second aspect of the invention includes a receptacle for a submersible electrical connector having a fluid - filled bladder which encloses a plurality of electrical socket assemblies identical with the one illustrated in fig1 - 6 , and described above . the receptacle illustrated in fig7 , and 9 includes a receptacle shell 57 enclosing a fluid - filled bladder 58 . the receptacle 57 includes an elongate sleeve 65 , which is a substantially cylindrical piece having a rear portion with four through bores , each bore accepting the end of piece of a respective electrical socket assembly . in the description which follows , it is assumed that the electrical socket assemblies disposed in the receptacle shell 57 are identical to the one illustrated and described above . for convenience , the one socket assembly shown in side elevation in fig7 is assumed to be the electrical socket assembly 10 of fig1 - 6 . continuing the description , the electrical socket assembly 10 is seated in the rear portion of the elongate sleeve 65 in one of the four through bores provided through the sleeve rear portion . the electrical socket assembly 10 is seated by engagement of its load bearing shoulder 40 against a load bearing seat 66 in one of the through bores . the socket assembly 10 is retained in this position by the snap ring 38 . the rearmost portion of the rear piece 22 , that is , the portion wherein the solder pot 42 is located , projects out from the rear of the sleeve rear portion . the bladder assembly 58 is formed from a flexible , elastic material such as natural or synthetic rubber ; it is maintained in an elongated , cylindrical configuration by a bladder stretcher , or support , 70 ( fig1 ). as can be seen from fig1 , the stretcher essentially consists of a pair of spaced annular portions 70a and 70b separated by a pair of support spacers 71 . the bladder 58 , with the stretcher 70 inserted into it , is placed in the interior bore of the receptacle sleeve 65 . an end cap 72 ( fig7 and 11 ) retains the bladder assembly in the receptacle sleeve bore . the end cap 72 is retained by a snap ring 74 , at the forward end of the interior bore of the shell 65 . the structure of the receptacle shell 65 includes a mating key 76 on the outer surface of the sleeve 65 , mating threads 78 at the bottom of the sleeve 65 and an enlarged - diameter shoulder 80 aft of the threads 78 . grip rings 82 are formed behind the shoulder 80 , and boot seals 85 are provided to provide fluid and pressure seals against the rear extensions of the rear pieces in the four electrical socket assembly disposed in the receptacle 57 . the structure of the bladder assembly includes a rear seal 90 formed against a rear seal seat 91 in the rear portion 70b of the spacer 70 . an end seal 94 is formed in the forward end of the bladder assembly . the end seal 94 of the bladder assembly includes four through passageways , or holes , that are aligned with four corresponding passageways , or holes , of the forward end of the stretcher assembly 70 by means of an end seal alignment key 96 on the stretcher . the alignment key 96 is received a corresponding keyway 98 of the end seal 94 . the alignment key 96 is shown in fig7 and 8 , and the keyway 98 in fig9 . one of the holes 102 in the end seal 94 is shown in fig7 aligned with a corresponding hole 100 in the spacer assembly 70 . the end cap 72 is also bored through with four holes 106 , which are aligned to the holes of the end seal 94 by an alignment key 104 . the alignment key 104 is seated in a corresponding keyway ( not shown ) in the end seal 94 to orient the holes 106 with the holes 102 in the end seal 94 . as seen in fig7 the end holes 106 of the end cap 72 are tapered at 108 . the tapered surface 108 provides for guidance of a probe into the holes 102 in the end seal 94 . the end cap 72 is mounted in the shell 65 to compress the end seal 94 , thereby adding to the radially constricting force that the end seal applies on the holes 102 . an annular void 109 is formed between the end seal 94 , the rear of the end cap 72 , and the interior surface of the receptacle sleeve 65 . the void 109 provides a space for the end seal 94 to slightly deform into , if necessitated by the passage of a probe into one of the holes 102 . the bladder assembly is filled with the dielectric fluid which also fills the the module 12 ( and each of the other three modules in the shell 65 ). the void 109 is vented to the outside environment through grooves 110 in the end cap 72 ( fig1 ). the exterior surface of the fluid - filled bladder assembly 58 is vented to the outside environment through vent holes 92 in the receptacle shell 65 . the venting provides for equalization of the pressure between the outside environment and the interior of the fluid - filled bladder assembly 58 . this pressure equalization virtually eliminates pressure differential across the seals in the socket assembly 10 and the end seal 94 . as shown in fig7 the electrical connector assembly 10 is disposed inside the bladder assembly 58 in alignment with an aligned set of holes including a spacer hole 100 , an end seal hole 102 , and an end cap hole 106 . it will be evident that four sets of aligned holes provide a corresponding set of ports opening into the bladder assembly 58 . for the respective port illustrated in fig7 the electrical socket assembly is held in the receptacle shell and in the bladder assembly in alignment with the port . the socket assembly 10 is held in the receptacle by the snap ring 38 , the assembly 10 being aligned with its respective port by the engagement of the shoulder 40 with the seat 66 . the o - ring 36 seal the through bore in the rear portion of the receptacle sleeve to prevent fluid flow between the outside of the sleeve and the interior of the bladder . the alignment of the socket assembly 10 with the port consisting of the holes 100 , 102 , and 106 provides for the extension of the stopper tip 21 through the port . this is best shown in fig7 . each of the other three ports ( not shown ) of the receptacle of fig7 is similarly aligned with a respective socket assembly and receives the stopper tip from the aligned socket assembly . it will be evident that the stopper tip 21 acts as a stopper both for the electrical socket assembly module 12 and for the fluid - filled bladder assembly 58 . thus , for each socket in the mu - ti - socket receptacle 57 , there are two , independent fluid chambers , one contained within the other . one fluid chamber is the chamber formed by the module of the socket assembly , the other chamber being the larger bladder assembly 58 . since the bladder assembly 58 is filled with dielectric fluid , each chamber is electrically and environmentally separated and isolated from the other three sockets . now , one will appreciate that as a probe is inserted into the port illustrated by the cutaway portion of fig7 it contacts the tapered surface 108 , and is guided through the opening 106 into the end seal hole 102 , where it contacts the concave face 34 of the stopper tip 21 . when the probe engages the concave face 34 , it pushes the stopper rearwardly into the socket assembly 10 ; thus , as the probe is inserted through the end seal 94 into the socket assembly 10 , it displaces the stopper tip 21 , under pressure from the spring 30 , as described above . also , when the probe is withdrawn from the receptacle port , the stopper tip 21 follows it back through the port . thus , the end seal 94 , being formed of an elastic material which is in compression , exerts a constricting force on the hole 102 . the constricting force closes the hole 102 into a sealing engagement with the stopper tip 21 , or with a probe tip . as with the forward passageway of the entry lip seal of the socket assembly 10 , the end seal hole 102 is never required to compress so far as to close the hole 102 . since , as described above , the tip of a probe has a slightly larger diameter than the stopper tip 21 , the insertion force required to place the probe tip contact with the connector surface inside the socket assembly and is minimized . at all times , the compressive end seal feature of the bladder assembly 58 maintains a barrier between the interior of the bladder assembly in the external environment in which the receptacle is deployed . the compression of the end seal 94 also acts to wipe the exterior surface of a probe clean when the probe is inserted into and extracted from the receptacle . the plug portion of the connector of the invention is illustrated in fig1 . for this embodiment , the plug assembly 120 includes a dielectric plug body 122 with four conductive elements , one of which is illustrated and indicated by 124 . the conductive element 124 transitions to a conductive tip 126 at its forward end and , at its rearward end , to a solder pot 136 . the plug body 122 is formed of a non - conductive material , while the conductive path consisting of the conductive tip 126 , and the element 124 is formed of a conductive material , preferably a metal . the end portion of the conductive element 124 is sealed by a boot seal 135 . as illustrated in fig1 , construction of the plug body 122 includes formation of a dielectric outer probe shell 132 , which tapers at its base 134 . the combination of the probe outer shell 132 with a tapered base 134 and the conductive tip 126 forms one of the four probes of the plug in fig1 . the other three probes are identical with the probe illustrated in fig1 . the tapered base 134 of the probe shell 132 enhances the mechanical reliability of the probe by increasing its strength . further mechanical enhancement is provided by an enlargement 142 of the conductive element 124 . as shown in fig1 , the plug body 122 is provided with grip rings 140 for ease of handling . these rings also enhance the strength of the bond between the material of the plug body 122 and the conductive elements . the plug body 122 has a mating keyway 128 with a flared entrance , 170 , which engages the mating key 76 on the receptacle sleeve 65 of fig7 . when the plug body is brought together with the receptacle of fig7 the plug body 122 is turned until the alignment key 76 is engaged by the flared opening 130 . the plug body and receptacle shell are pushed together axially , while being slightly rotated on axis to enable the alignment key 76 to traverse into the narrow portion of the key way 128 . the alignment of the fig7 receptacle in the fig1 plug assembly by way of the key 76 and key way 128 aligns the probes in the plug assembly with the ports in the receptacle assembly , so that each probe in the plug assembly is repeatedly mated with a respective socket in the receptacle assembly . further , the alignment provided by the key 76 and keyway 128 orients the probes in the plug assembly with the end cap holes , so that each probe is initially aligned with a contact hole for being received into a respective end seal port . the plug body 122 is assembled to a plug body locking sleeve 164 by means of a snap ring 162 which holds the rear lip 161 of the sleeve 164 between itself and a shoulder 165 in the plug body 122 . the snap ring 162 is retained in an annular groove 160 formed on the rear portion of the plug body 122 . mating threads 166 are provided on the front inner surface of the locking sleeve 164 , while the difference in diameters between the bore of the locking sleeve 164 and the forward extension of the plug body 122 provide for a small space 168 between the sleeve 164 and the body 122 . the locking sleeve 164 is vented to the outside environment through holes ( not shown ). this venting provides an unobstructed path between the surface of the bladder assembly 58 and the ambient environment when the receptacle and plug are mated . the ambient pressure reaches the bladder surface through the holes in the locking sleeve and then through the vent holes in the receptacle shell . the connection between the receptacle of fig7 and the plug assembly of fig1 is illustrated in fig1 and 14 . as described above , the alignment key 76 is engaged by the keyway 128 to provide an initial alignment between the probes in the plug and the ports in the receptacle . the plug and receptacle are pushed together , with the threads 166 of the plug assembly engaging the threads 78 of the receptacle to retain the two connector halves in a mated operative engagement . as the two halves are brought together , each of the four probes in the plug assembly is aligned with and mated to a respective one of the four electrical socket assemblies . since the manner of engagement between probe and socket is the same for each of the four probe / socket pairs , one description is given for the engagement of the probe tip 126 with the contact ring 28 in the socket assembly 10 . as the connector halves are brought together , the probe tip 126 contacts the tapered surface 108 and is guided by it into contact with the concave recessed face 34 of the stopper tip 21 . the probe tip 126 pushes through the end seal hole 102 , the hole 100 , and into the forward passageway in the entry lip seal of the socket assembly 10 . eventually , when the two connector halves are fully seated , the probe tip 126 has traveled into engagement with the connector ring 128 , pushing the stopper tip 21 into its retracted position inside the electrical socket assembly 10 . electrical conductivity is thereby established from the conductive element 124 through the tip 126 , the ring 28 , forward piece 26 , tube 24 , and end piece 22 . the spring 30 is fully compressed . when the two connector halves are demated , the probe tip 126 is withdrawn from the interior of the socket out through the port consisting of the holes 100 , 102 , and 106 , while the stopper tip 21 is urged by the spring back 30 out through these holes . obviously , many variations of the invention are possible in light of these teachings which , when employed , will not deviate from the scope of the appended claims .