Yeah, sorry to have been a bit negative about Galapagos. You probably are doing it the best way (or at least the best way that they will allow).
You should probably take a lightweight wet suit for snorkelling. Water temperatures are down at all times of the year compared to the BVI as the water mainly comes up from the cold southern ocean. This cold water does keep the islands at very comfortable temperatures even though you are right on the equator so that is a good point. Water was incredibly clear and full of life so snorkelling was always fun.