need to be fit?

[Torchwatch]

Weak and non swimmers entering the water are more likely to get into difficulty and less likely to be wearing speedos or square cuts.
This might unbalance the safety aspect of wearing board shorts in the sea.
Also board shorts wearers may not have planned entering the water and are more more likely to have been drinking than speedo or square cut wearers who have planned to go to and into the water.