Tried it in Barbados a few days ago – highly recommended. The day after the World Cup final, we hit the Paynes Bay beach in western Barbados. One of the attractions there was snorkelling with sea turtles. The routine goes like this : you clamber aboard a boat that takes you a little way into the sea, you pull on your snorkel and fins and jump into the water, the boatman throws chunks of fish into the water and soon you find a number of very large turtles swimming gracefully around you. Awesome.
The last time I saw sea turtles at such close quarters was in Lakshadweep. These creatures that look so ungainly on land are a delight to watch in the sea as they glide effortlessly past. They belong there and we dont.
Here is a video I found on Youtube which should give you an idea of what I am talking about