My girls are 20 & 21 now. Two years ago on the Sensation, they had no trouble getting into the "mature" comedian's show at midnight. One of them was legal to go into the casino, but when we took the other one with us, no one said anything. Since 18 is the legal age for everything except drinking, I'm sure they will have no problem going anywhere on the ship. I've heard that if you are with the underage ones, the parent can order a drink for them.........if that is an issue for you. Mine were too old for the teen club thing too and they just sort of formed their own group with some other older teens. They did go to the disco, but of course couldn't drink. I don't know if they could have because they do look older than they are, but they didn't. We do allow our 20 year old to have a drink with us at home as long as she is staying home and not going anywhere. This will be an issue with her on the cruise because she is going to want a frozen umbrella drink around the pool..............awkward age, huh???