What prevents scuba divers from going deeper than 40 meters below the surface?

The pressure of the water and the feeling of being suffocated 

As you go down, there is more water pressure pushing down on you.
It's like how if the football drops and the whole team jumps to get it and you just happen to get crushed on the bottom. The pressure of the other players will most likely break at least something in your body.
I'm just guessing that if you go lower than 40 meters, then there might be so much pressure, that they might die.

Water flows along the east coast and across the western tropical pacific towards south america, while they both are directed towards that way,  el niño does not directly affect the southern flow of water along the coast. 

Answerepicenter;