Hi not sure where you want to cruise!!but if its the Med you are looking at,try RCI Voyager of the Seas
took our Grandson who was 12 at the time and had a wonderful time the cruise was out of Barcelona,stayed
2 nights pre cruise and did the tour of Camp Nue [Barcelona Stadium]
lots of sports on the ship also ice skating ,rock climbing,and great swimming pools.

I have just come back from a Thomson Cruise on the spirit, there were in fact a few grandparents taking their grandkids away one couple I met had a 15 year old - although the 15 year old did say that he prefered Ocean Cruises as there were more to do for younger people, I have not tried Ocean so can't say. I Have looked at the web site before and they do seem to cater for young folk with the various ports activities etc.

Hope you find something

Royal Caribbean would probably fit the bill. Have a look at our Cruise Reviews to see if any of the ships appeal to you.

luci

tbhanks for all the imfo