Bali waters are kind of murky. If you want snorkeling, I'd recommend PALAU. Nice clear blue waters. Saipan had some nice snorkeling as well, along with Guam and the Marianas. But Palau takes the cake. Bali is a party place. Kuta beach but most activities regarding the ocean is usually surfing there. Not good for snorkeling. I can't speak for Thailand though I'm sure some of those islands there are nice for that.