If you get the chance to SUP (stand up paddleboard) while your on the island please do!
This is one of my favorite ways to be on the water. I am not a diver, love to snorkel, but most fun to me is the relaxing time on a board. The water is so crystal clear and to glide over fish and see the sights of town from the perspective of the water is really neat.
You can arrange for lessons one morning from Raul of De Lille Sports and he'll have you on the water in no time. I think if you look they have a Facebook page.
I like that if I don't feel like standing and paddling I can kneel or sit and still enjoy my time. Secretly, I love the sunsets while sitting on a board and holding a cold "beverage".
I know there are other options out there for paddleboarding but I feel more comfortable sharing the info I know first hand.
However you do it please give it a try cause I know you'll love it.