Some friends asked about tours which are bought onboard the cruise ships - and wether independent operators still carry those tours when the cruise lines CANCEL them because of various reasons - mostly bad weather. PLEASE understand that perhaps the best example of cancelled tours is CAVE TUBING. If the ships cancel DO NOT DO THIS TOUR.
One independent operator who has only been on the scene in Belize since October of 2005 DID carry a busload of guests, and DID the tour despite the best advice of others and of the very wardens at the park site, and they nearly lost some people (including children!!). Everyone on that tour, including some of the guides, ended up with some type of injury. Other more experienced guides at the site that day had to go to their rescue. That day's activity by this particular operator flew in the face of the very website details they flaunt "their tours, our tours" "Not safe, and safe"!!!!
The tour is a safe and extremely wonderful tour, but it must be done when the river is in its most usual state - low and green. So, if the ship says no way, please do the same - flooding or unsafe water levels on this tour happen very rarely, but they do happen. There are lots of other sites in Belize to visit, especially as substitute tours. LOTS!!!! If you have any doubts, especially for this particular tour, ask the operator about their background, time done on this tour, and sass it out for yourself. There are several operators with lots of years of experience (and can prove it), while others may bamboozle their way into a tour from you. Stay safe and sound - enquire, enquire, enquire. Sometimes a good GOOGLE search will turn up excellent background and timeline information.
Belize is still noted as a very safe and popular destination, but just make sure you are careful about whom you choose to take you on tours that are more involved than most, especially where water is concerned, and particularly where caves are concerned. By the way, the people in Belize who control the cave site are called NICH - the National Institute of Culture and History. They have now inserted a metal pipe into the beach at the cave site, with special red markers up the pole - the last red marker means "NO WAY, JOSE". Good system. You can actually check it our for yourselves.