Castaway Cay for toddlers?

[Emsabems]

I am sailing on the Wonder in September, with DS 3 and DS 5. Both like the water but are not swimmers yet - they are comfortable in their life jackets to some extent. We've been taking a mask and snorkel to the pool, the bath, anywhere we can think of with water, as I'm really hoping they will get to 'snorkel' or at least put their masks in the water and see some fish!

So here's the question - is there a place to see fish that is close enough in that we might be able to paddle/raft out to and see some fish? Anyone with pictures and a good description of the water at Castaway would be much appreciated!

Emsamom