If your group like to snorkle then the beach at Mahagony Bay is nice but not good for that, For that go to Tabanaya Beach the reef is right at the beach and is beautiful. We did a snorkling excursion at Belize that if the water had not been so rough would have been real nice, it is along the channel that the ships use.
And Grand Cayman has many nice beaches.
Caribbean Trip Reports
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013, Carnival Legend Nov 2013, MSC DIVINA Jan 2014, MSC Divina Oct 2014