1. Water is indispensable on board, so as long as seafarers working on board learn to use life jackets, there are requirements on board. Unless they don't need to wear it in the living area, they must wear life jackets at other times.

2, and every once in a while to exercise, the exercises on board are not deceptive, all are real simulations, and sometimes there are relevant departments abroad to check, so the sailors have developed an inertial thinking and integrated with life jackets. Even if they accidentally fall into the sea, even if sailors can't swim, they can be guaranteed to float on the sea.

The sea or ocean is not suitable for swimming at all. Once a person is in the sea or ocean water, it is not swimming, but a scene of survival.