Dave brought up a good point about the biodegradable sunscreen. This is something you can easily order online. I used amazon.com when I ordered mine, and just searched for "biodegradable sunblock."
2007 - Majesty of the Seas (Bahamas)
2009 - Enchantment of the Seas (Western Caribbean)
2010 - Freedom of the Seas (Western Caribbean)
2013 - Golden Princess (Alaska, roundtrip from Seattle)