text: why does water and other liquids exert upward thrust (boyancy)?? why is the direction of the boyant force upwards???..........can u plz explain the archimidies principle pressure in fluid increases with the depth. the strange thing with pressure is that it works in every direction. so the water above 5 meters is pressing downwards on the water beneath the 5 meters and the water beneath the 5 meters is pressing upwards on the water above. because it is the same depth the upward and downward pressure is the same. if we put an object into a fluid the fluid above the object is pushing it down, but the fluid beneath the object is pushing it up. because we are talking about an object now and not some imaginary plane, there is a height difference (depth difference) between the fluid pushing down and the fluid pushing up, so the pressure differs, thus the forces differ. the upward force will be larger then the downward force. it depends on the weight of the object in relation to this forcedifference however if it sinks or floats.