The most active volcanic crater in the solar system, Loki Patera on Jupiter’s moon Io, is thought to be a lava lake that periodically brightens because of overturning lava. A UC Berkeley team regularly monitors Io, and took advantage of a rare 2015 event, Europa passing in front of Io, to map the surface of the lake in detail. They found evidence for two massive waves of overturning lava converging toward the lake’s southeast corner.