The Wailuku River is the longest river in the state of Hawaii, and extends along the gaps formed by the volcanic flows of Mauna Kea and Mauna Loa. Wailuku State Park extends over a small part of the river, where you can enjoy hiking with your families and friends, and the area is famous for swimming, in addition to its charming waterfalls, and you can take a path along the river and enjoy the picturesque nature.