He's chased tornadoes. He even got married on an erupting volcano. As an adventurer, George Kourounis has seen many of nature's extreme environments. But a recent trek to the Central Asian country of Turkmenistan may be one of his most exciting expeditions. Kourounis was the first person to descend into a 30 meter (100 feet) deep pit of fire known as the "Door to Hell." The pit is a crater in a large natural gas field that has been burning for decades. It is said that an old Russian oil rig fell into the crater in 1971. Geologists were worried the pit was releasing poisonous gases. The scientists decided to set the pit on fire. They thought the gas would burn off quickly. However, the resulting gas-fed flames continue burning to this day. His team couldn't confirm the story behind the pit. Still, Kourounis definitely confirmed that the site exists. He had wanted to visit the Door to Hell for years after seeing pictures of it online. "It just never exited my mind," Kourounis says. Burning Challenges And Bureaucracy One of the toughest challenges wasn't the fiery pit itself. It was getting into Turkmenistan, whose government does not often give people permission to visit. After two years of trying, his crew finally entered Turkmenistan in 2013. Kourounis says the crater looks like a volcano in the middle of the desert. It's about 76 meters (250 feet) wide, nearly as long as a football field. "Day or night, it is clearly burning. You can hear the roar of the fire if you stand at the edge," he said. He added that being near the heat is unbearable. "There are thousands of little flames all around the edges and toward the center. Then there are two large flames in the middle at the bottom," he says, probably where natural gas used to be drilled for. Before going into the burning pit, Kourounis got his equipment together. This included a climbing harness made out of Kevlar, a very hard material. He also had a breathing machine, similar to a tank for scuba diving. His rope and suit were made to resist heat and flames. The suits look like aluminum foil and are used by workers who are often near flames, like firefighters. They help reflect heat off of you, but "you still get pretty hot inside," Kourounis says. He also commented he felt a bit like a baked potato wrapped in his foil suit. Another special tool that Kourounis brought to Turkmenistan was to measure how hot the ground was. "It sort of looks like a sword," Kourounis says. It could wirelessly transmit the temperature of where he was. Entering The Door To Hell Even after preparing, Kourounis says the idea of descending into the Door to Hell made him nervous. Still, he did drop into the fiery hole. "It wasn't dark at all," Kourounis says of the crater's interior. "You are surrounded by flames, so everything has this orange hue." The most important part of the mission was to take some samples of the soil and sand at the bottom. From this, Kourounis' team would see if there were any tiny bacteria living at the bottom. These life forms could provide clues about life in these extreme environments, Kourounis says. These tiny bacteria are microorganisms known as extremophiles because they can survive in extreme environmental conditions. Extremophiles survive in incredibly hot, cold, salty, acidic or dry conditions. The ones at the Door to Hell appear to be "enriched" by the high temperature and low nutrient levels, among other things, says Dr. Green, a scientist on the trip. There's a good reason for Kourounis to do this risky work. He says it could help us learn about possible life on other planets. Many faraway planets have hot, desertlike environments. They are not too different from the fiery crater's landscape, he said. He wants to know if any life out there has found a way to survive in such extreme places. Basically, he said, they "were looking for alien life right here on Earth." The soil samples were given to Dr. Green, who studies tiny life forms. It turns out there were new tiny life forms in the crater. They were able to survive the high heat in the Door to Hell. The fiery pit feels like being on another planet, too, Kourounis said. Its orange and red soil reminds him of Mars.