The reason may be silly,but they determined in their infinite wisdom that swimming more than 15M underwater caused a risk of passing out.This would happen back when it was legal to swim breaststroke underwater so there is some rational to it,but 15M is arbitrary.
The reason may be silly,but they determined in their infinite wisdom that swimming more than 15M underwater caused a risk of passing out.This would happen back when it was legal to swim breaststroke underwater so there is some rational to it,but 15M is arbitrary.