I visited this WHS in Spring 2024 staying close to Half Moon Caye Natural Monument and the Blue Hole Natural Monument. Already getting close to Half Moon Caye, we got lucky and from the boat we saw a couple of dugongs feeding in the middle of the mangroves. If you stop by the mangroves, make sure to wear some mosquito repellent, and beware of crocodiles!
Staying close to Half Moon Caye, meant we were able to come and go at different times of the day with rather short boat trips to enjoy the island and reefs mostly alone. On the island proper, there's a beach which is practically reserved for nesting turtles and a broken down lighthouse where a lot of water birds like to stay. On the opposite side of the island is another lovely beach for swimming, lots of coconut palm trees, a small ranger station with some information boards, and a short hike through the lush vegetation and mangroves, full of hermit crabs, iguanas, lizards and a wooden watchout tower to view the scores of frigatebirds and red-footed boobies and their young in this bird sanctuary. There is a UNESCO WHS plaque for both Half Moon Caye and the Blue Hole Natural Monuments near the Half Moon Caye quay.
We saw lots of different coral, rays, lobsters, conches, moray eels, fish and reef sharks around Half Moon Caye, although snorkelling at the Blue Hole Natural Monument was much better overall with schools of fish, almost as if they were scared to venture too far from the edges of the Blue Hole. In fact, those who dived inside the Blue Hole were more impressed by the stalactite formations rather than for the marine life in such depths. The cherry on the cake to finish off our visit was the scenic flight over the Blue Hole with Tropic Air. Everyone gets a window seat and the pilot goes round the Blue Hole a number of times to make sure everyone gets a chance to take enough photos and videos. It really is a sight to behold and worth the extra time and money. Unfortunately there isn't the option to go for a scenic flight without windows as is the case at the Rock Islands of Palau. When compared to other scenic flights, although enjoyable, it pales in comparison and there are also a number of rusty (unsunken) shipwrecks stuck in the reef.
Also, most locals seem to really dislike European travellers and very much prefer having groups of time-pressed American cruiseliner passengers to easily squeeze their dollars with the least effort. This was our experience at most shops, hotels, bars, etc. we visited and during most services we paid for such as taxi rides, boat rides, groundhandling, flights, etc. Luckily it seems unlikely that Belize will ever get anything else inscribed, so I won't be returning any time soon.