Browsing the WWW for cruise related stuff and came across the subject of age limits. I came across this page about age limits for unaccompanied traveling. I thought it was interesting that most lines require under 21 to be accompanied by someone older. Yet "Ultra-Luxury" line except SilverSeas and Windstar say it's okay for 18-20 yo to travel alone. (Cunard and Disney say 18 and over is fine as well). I'd think it be the other way around.
I thought it might lead to an interesting discussion.