How deep can you dive without gas?
Safe limits for mix of gases in trimix are generally accepted to be a maximum partial pressure of oxygen (PO2—see Dalton’s law) of 1.0 to 1.6 bar and maximum equivalent narcotic depth of 30 to 50 m (100 to 160 ft). At 100 m (330 ft), “12/52” has a PO2 of 1.3 bar and an equivalent narcotic depth of 43 m (141 ft).
Why do divers dive backwards?
Just like using a diver down flag, diving back into the water is a standard safety technique. … Backward diving allows scuba divers to keep a hand on their gear while entering the water to avoid losing a mask or getting lines tangled.