Belize City is very poor but it seems like everyone on our ship went cave tubing that day and it was a blast. We booked our trip through a company online (not the cruise ship and it was 1/2 the price). I know people think this is crazy but check out tripadvisor.com, it's totally safe and we had a great time. I also heard people took an excursion to a key off of the mainland and really enjoyed it. I wouldn't think about leaving the port on your own though, it's not safe. So make sure you have something planned for this port before you dock, it's a great stop if you're prepared.