I am not a diver, but on my second cruise we pulled into the Maldives Archipelago for a week.
We stayed on a small island in the chain and I got the opportunity to snorkel off the reef faces, etc. I had snorkeled a lot before the Maldives.
I couldn't believe it: The clarity of the water and life below the surface was unlike anything I had previously experienced.
My OinC on the Detachment was a diver and brought his equipment on cruise. He said it was the best diving experience of his life.
That was in 1987. Things have no doubt changed but there it is.
http://www.padi.com/scuba-vacations/maldives
Enjoy!