Wait a minute. You're a college student, and you're concerned about drunk 20 year olds?
Actually, a cruise is probably not much different from any resort destination where alcohol is served. As far as drinking goes, there was quite a bit of it on board the Rhapsody when we sailed last September, but nothing that caused a problem. This ship sails from the Texas coast and is usually (as I understand it) at least 50% Texan. Texans (I am one, so I know whereof I speak) are known to get their sip on, on occasion.
In any event, our cruise (not in the summer and not at Christmas) was a nice mix of mostly couples from their 20s to their 50s, some singles, some teens and a relatively small number of kids.
The thing is, there are so many different areas of the ship, the pools, the spa, the casino, the various lounges featuring different types of music, that if you want a quieter crowd, you can find that and if you want to party like your mama won't find out, you can find that scene too.
) Have fun! We'll be sailing that itinerary in May this year.