About 200km west of Kilimanjaro, Ngorongoro Crater is a former volcano that is thought to have once rivalled Kilimanjaro in height, estimated to have been 4500-4800m tall until it collapsed on itself. Today, at 22.5km in diameter and 610m deep, Ngorongoro is the largest crater on earth, creating a unique environment for local wildlife. “Waterfalls coming down the caldera irrigate green pastures and fill a lake at the bottom full of flamingos and a huge fauna on its shores: lion, hippopotamus, buffalos, zebras, gnus, rhinoceros,” Vaché said.

Kelimutu’s three mysterious crater lakes attract both scientists and tourists to the island of Flores in Indonesia’s East Nusa Tenggara province. “One is emerald green, another dark red, and the third pitch black,” Vaché explained. Scientists say the colours come from the chemical reaction that occurs when the volcanic gases meet the lake’s minerals.

Nearby residents have a different take. “Locals believe that the lakes are the resting place of departed souls and change colour abruptly based on the flow of souls,” Sunni Mewati said. Despite scientific explanations of the colours, “the eeriness surrounding the lakes as a reservoir of souls remains” he added.

Hawaii’s volcanoes are known for their active eruptions and otherworldly landscapes. The youngest volcano in Hawaii, Kilauea has been erupting continuously since 1983, “so much so that the lava falls straight into the sea, creating fantastic forms of black rocks and insane smoke clouds”, Vaché said.

At the other end of the spectrum, Mauna Kea is around one million years old. It sits dormant, still impressing with its sheer size, rising 4,205m from the sea. “Mauna Kea in Hawaii is both incredibly beautiful and home to secret treasures, including a sacred frozen lake near the summit accessible only by [a six-mile, 10-hour round trip] hike,” said Lesly Simmons. “You can find snow in the winter and almost zero crowds. We ran into only one other couple hiking from the base to the summit when we reached Lake Waiau.”

Perhaps the world’s most famous symmetrical stratovolcano is Japan’s Mount Fuji, which has served as the muse for many artistic creations through the centuries. “[It’s] the national symbol of Japan: snow-capped, looming in the distance, cherry blossoms in the forefront,” Vaché said. Not only is the mountain itself beautiful and mysterious, but the Aokigahara forest on the northwest base of the mountain also inspires the imagination, as many local folktales describe the demons and goblins that haunt within. At least the mountain itself remains a safe haven – the low risk active volcano hasn’t erupted since 1707.