"The Water Content of Earth's Crust: Unveiling the Hidden Reservoirs"

A 2021 study estimates that there are approximately 43.9 million cubic kilometers of water in Earth's crust, making groundwater the largest reservoir of water globally after the oceans. This deep groundwater, largely isolated and salty, could provide valuable insights into Earth's past and support ancient microbial ecosystems, shedding light on the evolution of life on our planet and potentially on other worlds. The study's findings more than doubled previous estimates of deep groundwater, emphasizing the need for further exploration of water at great depths on Earth and other planets.