Rainbow Falls is located in Hilo. It is one of the most beautiful sites on the island. The falls are part of the Wailuku River and face the east therefore making them a perfect place to spot a rainbow on a sunny morning. The best time to go is between 8 and 10am to see the rainbows. There is a short hike to the top of the falls which is not wheelchair accessible. However, there is a great overlook that does have handicap access.
Regardless of where you choose to go, the Big Island is home to some of the most beautiful geological wonders in the world. The contrast of the destruction of the volcano to the rich rainforests show you that the island is in a constant state of change but life finds a way.