I went to Ambergris Caye (northern island, close to Mexico). Very beautiful place and the locals were so incredibly nice. There was no shore diving, because the locals use the water as a large part of their transportation the area between the reef and shore is busy with boats. Anyways, the reef is about 100 yards off shore. So getting to your dive site takes minutes. The nice part was getting on the boat, getting ready to dive right away, you get to your dive site quickly, you get right in the water and when you are done, you go back into shore for your surface interval. It lets you go back to your hotel room, get a drink or snack, go to the bathroom in your own room, change camera batteries, and even lounge by the pool. If you are interested, i stayed at the SunBreeze Hotel and did all my diving with Aqua Dives, which was right there on site. I have heard great things about Placencia (southern town, on the main land). The rides out to the dive sites are a little longer to get to, but there are seasons where you can dive with whale sharks.