The only river in Hawaii that is navigable, it originates from the middle of the island, winding through the island, and the two sides are calm jungles. On the Smith cruise, we drift on the Weiluya River to visit the Fem Grotto in the jungle. Weiluya River is a place that kayaking lovers like, many of them are family members, enjoying this tranquility through the original. The boat has a traditional Hawaiian song and dance performance, a round and pleasant ukulele, melodious rhythm, accompanied by a slightly swaying swing, let people fully integrate into Hawaii's summer afternoon. The boat docked in a small pier, everyone walked ashore, along the forest path to the Fern Grotto, the cave formed by natural lava, covered with ferns and tropical plants hanging in the air. Because of heavy rain some time ago, the cave was temporarily closed and inaccessible. This is the wedding site of the locals, the caves are like natural amphitheatres, where musicians play songs from the locals' weddings.