Some can hold their breath longer than others.
Provided they work as a team, they might be able to pull out of it. They'd have to pair up. One would have to be responsible for picking the drowned victim's body up, and lifting it's head above the water so that everyone else could, in turn, have their head above water.
Carefully, they'd then have to spiral outward until they reach the pool's perimeter so that they can all get out in unison.
Like I said, they have to work as a team... otherwise, everyone dies.
