"Rainbows and Waterfalls Just outside of Hilo is one of the Big Island's beautiful waterfalls. Rainbow Falls is a pretty sight, particularly when the sun is shining and its rainbow is shimmering in the mist. The rainbow is out on most days, so chances are that you will see it when you visit. There is a little trail that will take the brave (at their own risk) to the top of the falls, where visitors can climb the boulders around pools of water and stand at the top of the falls. Rainbow Falls is located in Wailuku River State Park and can be visited each day for free."