In its inaugural season, passengers as young as 5 months boarded Wilderness Discoverer. Parents should know their children's physical limits, though, as there aren't any special hikes or paddles geared toward kids. Noisy electronics, such as personal DVD players or video games, wouldn't be welcomed by fellow passengers looking to get away from it all; if you bring them, keep them in your cabin. And, while the kitchen does take some special meal requests, your children should be prepared to eat the same foods as adults during the trip.
Teenagers take to the ship's active itinerary with ease. Stand-up paddle-boarding in particular seemed to be a popular activity with the younger set, and many took advantage of the hot tub in the evenings.
(The line does offer Family Discoveries cruises on one of its other ships, Wilderness Adventurer, often with discounts for children 12 and younger. Activities on those cruises are tailored to the age and ability of the kids onboard.)