i've only been on 2 and almost all the cruisers were darn close to 40 or 40+ up to the 60's if i had to guess ages. i'd only say all bets are maybe off during the 8 week [?] college spring break window.at any other time you are not going to have 18-23 year olds.the longer and more expensive a cruise is would attract fewer young people too. i think the biggest spoiler of the cruise is if they don't have close to a 50-50 boy/girl ratio because you don't form groups who want to do things together.