1000 feet, how much meters is that?
My Seamaster can go to 300 meters.
The gas mixture is normally the air which is in the air filled into the bottles.
The pressure can be dense under water.
I saw on tv a submariner which exploded by the pressure.
A trained scuba diver can go i guess 800 feet.
I dived many years ago with bottles and the breath machine in a pool, so an easy place to dive.