It depends on how deep the diver goes, and what air blend the diver is breathing.
There are dive tables that state how long a diver can stay at a certain depth before requiring decompression.
The basic recreational diver typically breathes either air or Nitrox. There are separate dives tables for air and Nitrox.
A scuba diver.
aqualung, snorkle, SCUBA tank
You mean 'underwater' (one word) You can only dive into water. But I guess you want 'scuba-diver' ? or is your question this: What do you call someone who does 'snorkelling' ?
so the diver can breath.
There is a scuba diver power-up which you should use in water-related levels
So that the scuba diver could go more streamline in the water.
You need to take an Open Water scuba class.
they all like being in the water?!
You must be at least 10 years old to enroll in a PADI junior open water diver course.