Any object floats or drowns in water because of its density. Actually at the depth of any liquid, there is an upward force because of the effect of gravity on fluid. If an object falls on it, having less density than the density of fluid, it will float. If the object has higher density than water, it will sink down.
In the salty water of the ocean, objects can float easily because the dissolved salt adds mass to the water more, so density of it also increases. When an object falls in it, it will obviously have generally less density in comparison to salty water. So it can easily float there. The object of lower density than water in which it has fallen, floats to the top and submerges only by an amount as per the ratios of the densities. Fluid pressure will be the same in all directions.
