Is it safe diving or snorkeling during the rainy season in Bali?

It is not more or less safe to dive during the rainy season than during the dry season. It might depend on where exactly but generally it's the same in Bali. The current, for instance, can be stronger during the dry season than during the rainy season. The advantages of diving during the rainy season are fewer divers and snorkelers and the experience can be more unique. The underwater world is truly beautiful in both cases. Rainy season doesn’t mean rain all the time, it even sometimes doesn’t rain at all for many days and often it can rain only for one hour during the afternoon.