Freshwater springs can be found all over the Hawaiian islands, but rivers are fairly rare. O’ahu has one, though, the Waimea (Red Water). Waimea River flows into Waimea Bay, and both are wonderful places to visit for various reasons — the river can be paddleboarded and is full of visiting green sea turtles; the Bay is home to the famous Jumping Rock. But Waimea Valley, a short drive away from the beach, is worth the $18 admission fee.

The Valley has ancient and sacred significance to Native Hawaiian people. Visitors can learn traditional Hawaiian games, learn to hula, learn to make leis, see a reconstructed traditional village and agricultural site, and take botanic and cultural tours. Activities do change based on the day of the week, so if there is any activity you’re especially interested in doing, it may be worth calling the office to check what is scheduled when. A basic calendar can be seen here: https://www.waimeavalley.net/admissions/view/fees (scroll down to see fees and calendar information). Hawaii is much less formal than the mainland so it’s not unusual for plans to change with little notice, although museums and historical parks tend to be less guilty of this than small businesses. Still, better safe than sorry.

Regardless of which activity is scheduled for the day of your visit, however, there is always one thing waiting: the waterfall. Waimea Falls is one of very few waterfalls with a pool below that is both deep enough and safe enough to swim in. The park has lifejackets available and requires that visitors wear one for safety reasons, but since reaching the falls requires a short, but very hot, hike, squirming into one is worth it. You’re going to want the water’s chill after making the trek. It isn’t hard, but the Valley is extremely humid (which helps explain how green it is) and barring exceptional weather, you’ll be sweating by the time you reach the base. After that hike, the comparatively icy water is a godsend.

Remember to bring or wear water-safe shoes. The pool at the base of the falls is full of stones and getting in is painful without protective footwear. There is some food available within the park, but there’s a lot to do and look at and the muggy valley makes it easy to get hungry or thirsty quickly. Bring snacks, sunscreen, and drinking water (do NOT try to drink from the falls; it isn’t safe). You’ll definitely want a phone with a camera on hand. Bear in mind that theft is common in Hawaii so either plan to take turns with a buddy in the falls (someone watches things, someone else plays in the water), or use a waterproof bag or phone case so your camera doesn’t get ruined. And take your time! The valley and falls are one of the most stunning places on O’ahu, so enjoy it.