I had been under the impression the was no age restrictions over international waters, but can't find much to back it or not.
Here are some other threads on the topic:
http://www.flyertalk.com/forum/trave...l-flights.html
http://www.flyertalk.com/forum/archive/t-70159.html
http://www.flyertalk.com/forum/north...rinking-2.html
Probably more if you do a search