Sandals Whitehouse is a relatively new hotel in the Sandals chain, completed since 2000 I believe.
Negril has some good sites, Throne room among others.
If you do a search for Jamaica or Negril you should see a couple threads about Negril.
As for diving at Sandals oof it seems like a mixed bag.
Some people seem to have horrible experiences (short dives, lazy dm's, going to the same sites just off-shore over and over).
This could be isolated to particular hotels however?
Anyway I've never dove with them before so I can't give you a judgement based on personal experience.
However I can point you to several resources to help inform you and better make up your mind.
Participated in a thread recently on another board, only bring it up because of the widely contrasting experiences and opinions with Sandals by posters.
Have a look.
http://dive.scubadiving.com/talk/read.php?1,59175,60051#msg-60051
Honestly though I find it hard to believe that a chain that is known/purports to have such high standards in other areas would be so lackadaisical with regards to their watersports/dive department.
Buyer beware.
EDIT - Oh by the way there's a dive op in Negril, called Sundivers.
Haven't dove with them (yet) but might in the future with fellow members of my club.
http://www.sundiversnegril.com/
