a submersible floatation structure is formed of lengths of tubing which are interconnected by fittings . in one embodiment , the tubing end fittings are formed of a polymeric material , such as polyvinyl chloride . the tubing lengths and fittings are interconnected to form a selectable configuration , which , in some embodiments , may be in the form of a reclining chair , a raft , a buoy , or a life preserver ring . valves are provided for allowing water to enter the structure and thereby provide a ballast which serves selectably to submerge the structure , or render the structure for use on land .