Because "Monkey Business" at Banana Beach has a business deal with Ambergris Divers, directing their guests to them, I made all of my dives while in San Pedro with Ambergris. I'm an experienced diver (4000 hours +) and what I found was competent boat staff (skippers and dive masters), but an inadequately supplied shop (example: they provide only shoe fins, not the adjustable strap kind - a critical issue, in my opinion). Fortunately, I brought my own BC, mask and regulator; one of the other diver's Ambergris-provided regulator hose leaked at the tank connection - not a big deal, perhaps, but in my world, dive gear maintenance is imperative.
What I was particularly impressed with was the diligence of the Ambergris dive masters in protecting the coral and other organisms from impact by novice divers - an attitude not shared by at least one other dive businesses there - "L'il Alphonse" whose dive guides actually encourage their guests to do stupid things like pick up nurse sharks and hug them for photo ops. And this in a sanctuary area. Ambergris Divers should be the model for other dive companies in this regard.
For future Belize trips, I intend to go with enough diving friends so we can charter our own boat (with an experienced skipper) to go where we want and spend as long as we want. Tourist dive businesses are OK if you don't mind them making all the decisions which are based on management's bottom line. For what you get from Ambergris, for what they do, is a good enough value, however.
If you own or manage Ambergris Divers, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.