The boat we dived from was a pretty small boat. It was only a couple of feet from the boat to the surface. The waves were big, but when the wave pitched up, so did the boat, when it went down, so did the boat. We were never more than a few feet from the surface. As far as backroll practice, maybe try to find a dock or a boat to practice from before you go. If not, you will probably get a sort of trial run on your first checkout dive with the DM in more favorable conditions, assuming that is how your DM will have you exit the boat. Your setup and boat size and style may be different and you may end up doing a giant stride. If you do the backroll entry, just remember to take a hit off the reg before you enter to make sure it's on. Add a little air to your BC so you are buoyant at the surface, but not so much that you can't slip under the surface a little when you hit the water. You want to slip under the surface a little to ease the impact with the water. With one hand, cradle your guages and alt. air source so nothing snags on the boat as you roll into the water. The last thing you need is to have your guages or something ripped from your first stage as you enter. With your other hand, hold your mask on and your regulator in your mouth so they aren't dislodged upon entry. Make sure your fins are clear so you don't snag your fin on something in the boat and break your leg or something. Finally, look each way over both shoulders to make sure it is all clear so you don't fall on someone and konk them with your tank. Then just roll back and enjoy.
Also you might want to check out a book called "Lonely Planet Diving and Snorkelling Belize." It's a great book..very helpful. I describe the book's contents in two posts I made in Gaucho's thread in the Central & South America section of the board titled "Belize for the New Year - Help Please"
Also you might want to check out a book called "Lonely Planet Diving and Snorkelling Belize." It's a great book..very helpful. I describe the book's contents in two posts I made in Gaucho's thread in the Central & South America section of the board titled "Belize for the New Year - Help Please"