The Deep Sea
I wonder what prevents a fish that goes down to 100 meters from going down to 300 meters or 3000 meters. Does it feel an internal pressure that tells it to not dive further, or is it the amount of light or availability of food it seeks? Since fish wouldn't suffer from decompression sickness, I wonder if they could dive much deeper if they wanted to.<p>Now that I think about it, I've scuba dived to 130 feet and it didn't feel any different to me than being at 10 feet. The only reason I didn't go deeper is because the depth gauge, divermaster, and training told me not to go deeper, and not because I was feeling the pressure.