Robert M. Gary schrieb:

Do Scuba guys use O2? I thought they used air?

Of course they don't breath pure O2. However, some "advanced" divers
sometimes don't just use compressed air, but their own mixture. Even
more advanced divers sometimes use apparati which mix pure O2 with
whatever they want on the fly while under water.

So a specialized scuba shop might be able to provide you with pure O2.