Rainbow Falls is a waterfall located in Hilo, Hawaii. It is 80 ft tall and almost 100 ft in diameter. The falls are part of the Hawai'i State Parks. There is no fee to see the falls. At Rainbow Falls, the Wailuku River rushes into a large pool below. The gorge is blanketed by lush, dense nonnative tropical rainforest and the turquoise-colored pool is bordered by beautiful, although nonnative, wild ginger. Monstera is also in abundance.