A team of explorers claims that they’ve found a cave, called Hranická Propast, in eastern Czech Republic is the world’s deepest flooded fissure, going at least 1325 feet deep.
Polish explorer Krzysztof Starnawski, who led the team, told The Associated Press Friday he felt like a “Columbus of the 21th century” to have made the discovery.
Starnawski scuba dived to a narrow slot at 200 meter’ depth and then sent a remotely operated underwater robot, or ROV, that went to the depth of 404 meters, or the length of its cord, but still did not hit the bottom.
In 2015, Starnawski himself passed through the slot and went to 265 meters’ depth without reaching the cave’s bottom. After diving that far down, Starnawski had to spend over six hours in a decompression chamber. To explore the cave further, he needed a robot.