Lava tubes form when narrow lava channels crust over, build levees which arch over the channel and converge, or prograde through a series of toes at the front of a flow. Tube morphology is controlled by eruption rates, flow regime, thermal erosion, pre-existing tubes, and topography. Lava tubes are known from Martian regions of basaltic volcanism by surface ridges and collapsed tubes visible in Viking orbiter photographs, with the best evidence coming from Alba Patera and the Tharsis and Elysium volcanic provinces. Methods for searching for intact lava tubes include Earth-based very long baseline radar, orbital radar and photographic searches, kinetic penetrators, seismic surveys, and mobile surface exploration platforms.

Advantages of lava tubes as base sites are sheltered environments, constant temperatures, and freedom to use cheaper, lighter-weight construction materials and less shielding and insulation for humans and equipment in the base. Drawbacks include difficult access and possible distance from necessary resources. Issues to be addressed include volatile distribution and contamination of the tube atmosphere, structural properties of tube roofs, and geographic relationships with potential resources.