The hike up to Manoa Falls is pretty easy, but it's usually quite muddy, so wear sensible hiking shoes. Even small children should be able to make it up there though. You see lots of lush plants on the way up, & maybe meet a feral rooster or two.At the top you'll be rewarded with a view of the narrow, but fairly tall falls, and a pool that I expect you're not supposed to bathe in, but many do. I don't know if he still does it, but I met a local up there who hikes in each day and leaves a few crystals around for people to find.