from scitechdaily.com: NASA’s Hubble Space Telescope has observed water vapor above the
frigid south polar region of Jupiter’s moon Europa, providing the first
strong evidence of water plumes erupting off the moon’s surface.

Previous scientific findings from other sources already point to the
existence of an ocean located under Europa’s icy crust. Researchers are
not yet fully certain whether the detected water vapor is generated by
erupting water plumes on the surface, but they are confident this is the
most likely explanation.