I'd recommend Amigos Del Mar for your Blue Hole trip. Biggest boat, great people. I took the family with them last year and I was the only diver in the hole, which was probably a good decision on their part. It's too deep for kids (I did 144', swimming down to get to some sharks before I realized I'd passed 130--my computer alarm was set deep) and, honestly, it's not that big a deal. They do two other sites that day and they're both much better dives than the hole is. Chano (I think that's right) owns the boat and was captain that day, his son and two friends were aboard and all the kids had a ball snorkeling and jumping off the boat while we dove. The girls (10 and 13 at that time) did the other two dives as did my wife and they were thrilled with them. Great people, great boat (48', no one else approaches that length--that I know of), nice continental breakfast, great lunch...a good day, overall.
Sharks? Yep, that's part of the deal. We fed the ones we found deep coming up in the hole. Stopped for a safety stop at 20' and the divemasters fed them fish. They're pretty tame and know that, if they follow you up, they'll get fed.
Sharks very, very rarely attack divers. It's almost unheard of. Nurse sharks are what you'll see if you're snorkeling, more than likely. They're extremely docile, have rough sandpaper-like grinding plates rather than teeth and would much prefer to just lie on the bottom and let you swim by than even lift a fin. They're sweethearts. Most of the others near AC are reef sharks, not very big and not aggressive, either. I've never heard of a shark attack there.
On one of our trips between dive sites w/Amigos one day, the crew did spot a school of Mako sharks destroying a school of bonita--waaaaay offshore. They immediately backed down on them, we kicked the ladders in the water and took turns in the water--on the ladders with our masks on--watching the explosive feeding frenzy. It was incredible. The divemaster, Edwin, just advised us, "Don't let go of the ladder!" A great experience that, if you like sharks, is a very rare and a special memory.
I've seen a lot more sharks off the Keys in Florida than in any water off AC. Some of them I didn't much care for
, but we spearfish there and are competing with them for food, I suppose. I've never seen any that were threatening in Belize. Sharks, unfortunately, have a very unearned and undeserved reputation and, for the most part, leave you alone if you don't annoy them. Beautiful creatures, too.
Don't fear them off AC. You'll be safe.