Lava tubes are natural tunnels formed by flowing lava during a volcanic eruption. As the lava moves, the outer layer cools and solidifies, creating a crust while the molten lava continues to flow beneath. Once the eruption stops, the remaining lava drains away, leaving behind a hollow tube. These structures can vary in size, with some being large enough for people to walk through. Hawaii is famous for its lava tubes, such as the Thurston Lava Tube, which attracts many visitors. Lava tubes provide valuable insights into volcanic activity and the geological processes of Earth.