What does your son say about the situation. At 6 he's old enough to understand what he's doing and why. Did something happen that made him scared of swimming, or lose confidence? Also talk to the coach about this, or manager. Aquaducks is a large company there must be somewhere there who can give you some advice, afterall this is their line of work. It may even be better to perhaps pull your son out of classes and make an effort to take him to swimming pools for playing only. Forcing him to go and his fathers reaction will only make the situation worse.