I really enjoyed the Thalassotherapy pool on Mercury. You can buy day sessions or for cheaper by a pass for the whole cruise. If you are in a suite, you get free access to the T-Pool. Wear an old bathing costume as the water fades them.
Someone said to me that the Hot Rock massage was great too.
You will love Mercury
Mercury Western Caribbean November 2002
Galaxy Eastern Caribbean November 2003
Until Galaxy Panama Canal Out Of Galveston
13th November 2004