Remember Belize is a country. You will be in the harbor at Belize City. You will border a tender boat and take a ten to fifteen minute ride into port. In Belize check out independent companies like Coral Breezes or Ecological Tours of Belize.
We haven't been beyond the beach on Roatan so won't try to advise there.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014
Star Clippers: Royal Clipper 2015
West Bay Beach in Roatan is awesome for snorkeling! We did an excursion where we did the zip line and then they took us to West Bay Beach for snorkeling afterwards and it was a great excursion.
Our daughter did the zip line cave tubing excursion in Belize and spoke very highly about it.
Both of us were very glad we did what we did and did not do it through the cruise line, which is not as good, cost more, and was more crowded.
Both of us purchased our excursions through Shore Trips, but there are other companies also offering packages.
__________________ Travel Agent/Cruise Specialist w/12 yrs exp and 47 Cruises on 11 cruise lines! Favorites: Paul Gauguin - Tahiti: Uniworld River Cruises - Europe; Celebrity Solstice-class ships; Holland America - 12-nights Baltics & Russia; RCCL - 14-nights Greek Isles, Turkey, & Croatia; Holland America - 14-day Alaskan cruisetour; 10-night Canada/New England cruise; 21 days Hawaii w/7-night NCL cruise; Oceania - 25 days in Asia; more than 3 months touring Europe by train. And many all-inclusive resorts!