I think I might have replied to a post you had at another site but here goes anyway...lol
Kim - we were in Belize 4 years ago on a cruise. We elected to take a tour that took us thru Mayan ruins in the north part of the country and then closer to Belize City took a river excursion that was very interesting if you like wildlife and just seeing the countryside from somewhere other than a bus or car. The tour guide at that time told me that Belize City has some very interesting sites but that some of the downtown and old residential areas are not places to be wandering around on your own if you aren't familiar with the city. I would personally have no problem taking a guided tour of the city and wish that we would have had the time. Our tour was about 8 hours and we used up every minute of it and loved it. The boat on the river tour brought us back to the pier where the ship's tender had dropped us off. The harbor at Belize City is quite shallow and not suitable for cruise ships tying up to the pier. Plus, the pier that we were brought to was just plain not large enough anyway. Prior to anchoring you can see the ship's propellers churning up mud from the bottom of the ocean, so you know it IS shallow. My understanding is that most of the diving and swimming sites for cruises are located on the offshore barrier islands. I talked to people from our cruise who greatly enjoyed the clear waters and the reefs there. I have read comments that on very windy days some of the dive and snorkel locations are not accessable and tours have been cancelled AFTER you arrive at the site. If you go to your right from the pier where your tender drops you off in Belize City and go about 4-5 blocks, there is a very spartan, open park that doubles as a market on days when cruiseships are in port. Trinkets, shirts, hats, carvings, etc can be found at small booths that pop up all over the one end of the park near the bandshell platform. The park is surrounded by a residential area and the ocean comes right up to one end of it - separated by street. Friendly people and also a good police presence between there and the pier, so I felt very comfortable walking in that area. I would go back to Belize in a minute. Remember also that english is spoken by almost everyone there as well as spanish. Hope you have a great time!!!