Planetary caves from Mercury to Pluto?

On Earth, caves are unique environments at the intersection of geology, climate, and biology. Given that the same terrestrial speleogenetic processes exist throughout the solar system, it would be surprising if caves beyond Earth did not exist. Thousands of potential cave entrances (or subsurface access points) have been identified from Earth’s Moon to Pluto’s moon, Charon. To date, our most comprehensive knowledge of these potential subsurface access points is for the Moon, Mars, and Titan, which collectively contain more than 20 thousand features. Missions are either ongoing or planned for these three planetary bodies. One of these missions may ultimately detect a cave and potentially confirm it contains a laterally trending passage.