laavakäytävät
Laavakäytävät, also known as lava tubes, are natural underground geological formations formed by volcanic activity. They are created when molten lava flows from a volcano. The surface of the lava flow cools and solidifies, forming a crust. The molten lava continues to flow beneath this crust, eventually emptying out and leaving behind a hollow tunnel.
These subterranean passages can vary greatly in size and length, with some reaching several kilometers. The
Laavakäytävät are found on Earth in volcanic regions worldwide, and similar structures are believed to exist