Mountain Tubing in Kauai

Kauai Backcountry Adventures. Very popular with all ages, this laid-back adventure can book up two weeks in advance in busy summer months. Here's how it works: you recline in an inner tube and float down fern-lined irrigation ditches that were built more than a century ago—the engineering is impressive—to divert water from Mt. Waialeale to sugar and pineapple fields around the island. Simple as that. They'll even give you a headlamp so you can see as you float through a couple of stretches of covered tunnels. The scenery from the island's interior at the base of Mt. Waialeale on Lihue Plantation land is superb. Ages five and up are welcome. The tour takes about three hours and includes a picnic lunch and a swim in a swimming hole. You'll definitely want to pack water-friendly shoes (or rent some from the outfitter), sunscreen, a hat, bug repellent, and a beach towel. Tours cost $99 per person and are offered morning and afternoon, daily. 3-4131 Kuhio Hwy., across from gas station, Hanamaulu. 808/245-2506 or 888/270-0555. www.kauaibackcountry.com.