We used cave-tubing.com (Yhony and his guides) in October 06. We were all very impressed with the whole group of guides. They were very polite and quite entertaining. The bus trip to the caves was really nice with the guides filling us in on their culture, even giving us shots of cashew wine. We laughed more that day than the whole week combined.
ALSO they require NO PAYMENT in advance. They do not take your money until after the tour, this ensures that you have a great time and they work hard for their money!
October 1997 Princess (Bahamas)
October 2000 Carnival Tropicale
October 2006 Carnival Miracle
October 2009 Carnival Legend