Please lookup oxygen toxicity because diving on pure oxygen at depths of only 5 feet (1.5 metres) puts a diver in a range where convulsions have occurred which is extremely dangerous underwater. Diving as little as 6m depth is very likely to cause convulsions. Divers Alert Network (DAN) is the world authority for Diving related health expertise, they cover this subject thoroughly here:

https://dan.org/health-medicine/health-resources/diseases-conditions/oxygen-toxicity/#:~:text=Be%20aware%20that%20oxygen%20toxicity,have%20expected%20them%20to%20occur.&text=Whenever%20you%20breathe%20a%20gas,Ensure%20you%20have%20appropriate%20training.

Stay safe.

its meant for the pool and quick dives ( it only lasts 8 minutes)