It is very unlikely for scabies to be contagious in water. Unless, a person is already infected with Norwegian scabies, it is very implausible that the scabies mites would emerge from under the wet skin.
Scabies is an extremely contagious skin disease caused by tiny itchy mites. These mites, called as Sarcoptes scabiei, burrow deep into the top layer of the skin, where they breed and lay eggs. This causes intense itching and rashes on the skin of the host. People suffering from scabies rarely know that they have the condition until a few weeks after the infestation.