The pressure
Because there are much better salt water fish out deeper in the ocean. You would normally go about 40 miles out
the deeper you go, the colder the ocean water gets
the animals
increase
lower
Temperature decreases with depth.
In general, the answer is the water gets colder as you go deeper. But, there are exceptions. For example, at the Galapagos Rift there are intensely hot (hundreds of degrees) springs at depths of almost two miles.
i was told that it is the weight of the water around you
It can affect it because of how deep the current the more you go out in the ocean the more it gets deeper
The deepest ROV has been down to depths of around 6Km or 3.75 miles.
This is because ocean water has weight, and believe it or not, air has weight too. The water and air pressure add up when you go farther underwater. This causes there to be higher water pressure as you go deeper because the water weight adds up.