Even so, the cruise population remains weighted toward the 45-65 range and can go much higher. As a general rule, the longer and more expensive the cruise, the older the cruisers. Shorter cruises in the Caribbean tend to attract the youngest crowd, in part because they have the lowest prices. Some of my favorite table-mates have been older retired couples, people who loved to travel and had wonderful stories to tell. The passenger mix.
Different lines attract different passengers.
Costa is an Italian line that advertises heavily in South America and Europe. Yet when I cruised with them, many of the American passengers were complaining because the waiters spoke Italian and their fellow passengers were South Americans and Europeans. Ask your travel agent to make sure the sailing you want hasn't already been booked by some convention or incentive group, which tend to hog the public rooms. Plus, in my experience, something about the sea air convinces middle-aged male conventioneers that they look good in women's clothes. I don't know what it is about ship and drag, but I wish it would stop.