Water & ice spewing from Saturn's moon Enceladus in this 2005 Cassini spacecraft image. Credit: NASA/JPL/SSI; Mosaic: Emily Lakdawalla
"Ever since the Cassini spacecraft first spied water vapor and ice spewing from fractures in Enceladus’ frozen surface in 2005, scientists have hypothesized that a large reservoir of water lies beneath that icy surface, possibly fueling the plumes. Now, gravity measurements gathered by Cassini have confirmed that this enticing moon of Saturn does in fact harbor a large subsurface ocean near its south pole."
Learn more: Cassini Spacecraft Confirms Subsurface Ocean on Enceladus