Of course, besides needing a clean bill of health, another prerequisite is that you can't be afraid of the water. You needn't be a champion swimmer, but you can't have problems with panicking in the water.
當然，除了健康的身體之外，另一個先決條件是不能怕水，雖然不一定得先成為游泳高手，但至少對水不能有恐懼症。