A garbage collection watercraft includes a hull, a collection box, and a buoyant material. The collection box includes an intake port to receive garbage. The collection box is held by the hull so as to be movable between a collection position and a pull-up position. The collection box is at least partially located underwater at the collection position. The pull-up position is located higher than the collection position. The buoyant material is attached to the collection box. The buoyant material raises the collection box from the collection position to the pull-up position by a buoyant force.