To determine if the pit was part of a greater tunnel system ... But this large lava tube in the Sea of Tranquility might be ...

An underground moon cave that stretches ... could be a potential lunar base for future astronauts, according to scientists.

more than 18,000 km from their home base in Brisbane, to test their navigation and mapping technology with the German Aerospace Center (DLR) in a lava tube—a tunnel through rock, deep underground.