CATANIA, ITALY – MAY 28: Visitors rest next to hardened lava below the peak of Mount Etna on the island of Sicily on May 28, 2017 near Catania, Italy. Mount Etna is among the world’s most active volcanoes, with eruptions occuring frequently at the peak and among the approximately 300 vents spread across the mountain. Etna is among Sicily’s most popular tourist destinations. (Photo by Sean Gallup/Getty Images)