Off Hwy 9 east of the Zion–Mt Carmel Tunnel, Keyhole is a gem of a narrow slot that drops down three short rappels, interspersed with several cold, dark swims. Local canyoneering outfitters describe it as the route that offers the most bang for your buck. Relatively short (roughly two hours), it's a great beginners' canyon.

It requires a permit, 60ft of rope and a wet suit even in summer.