If you like whale sharks, the best time to go is obviously June to November. But if you are a fan of manta rays and prefer to see them, going December to May is the best.
In general, going in the humid season (June to November) does have advantages because it’s warmer, and some people say the ripples in the water from the rain attract sharks to the surface, because they can sense these kinds of things. Believe it or not, sharks can actually sense fish’s heartbeats!
So when the ripples attract more marine life, the depth you go to see the most awesome marine life is decreased, so you don’t have to go as deep.
Going to Cape Douglas and El Arenal are great, as mentioned before. Another exceptional dive site is Sharks Point, and one of it’s coolest animals is the whale shark. Also, hammerheads and Galapagos sharks travel in groups, and there’s a decent chance you’ll see some while diving there.
Gordon Rocks is a great place too. The main attraction is definitely the hammerheads, because the strong currents bring in lots of sea predators.
Because of these forceful currents you have to be cautious while diving there, because they can easily carry you away from your group. Diving in Galapagos, it’s a good idea to travel in groups instead of solo dives, so that you can make sure others don’t drift away!