Question

explain why deep sea divers have to wear very strong diving suits

Answer 1

At significant depth, divers might use an Atmospheric diving suit like this: as opposed to a wetsuit, or a Dry suit like this: The atmospheric diving suit is rigid, strong enough to maintain normal air pressure inside against dozens of atmospheres of water pressure on the outside.

Answer 2

since the pressure inside the fluids increase with the increase in the depth that is why divers have to wear special suits to protect their body from crushing.