In a number of historically and currently volcanically active regions on Earth are low-lying craters often filled with water called maars. The lake-size maars could be mistaken for meteorite craters. But they actually formed when there was contact between undersurface lava and groundwater resulting in a massive, steaming explosion blasting through the surface. After the blasts, many maars backfill with water. Studying the craters are an important part of understanding planetary surface formation and processes. Also, scientists have found that sediment core samples from maars provide great details for understanding Earth’s climate record and change. NASA platforms provide excellent data for finding and measuring maars across the planet.