CAVE VRELO - World deepest underwater cave, Macedonia

Located on the right bank of the Treska River, the cave was listed as one of the top 77 natural sites in the world in the New7Wonders of Nature project.
Vrelo Cave has many stalactites including a large one in the middle of the cave is known as the "Pine Cone" due to its shape.

 There are two lakes at the end of the cave, with one larger than the other. The smaller lake is 8 metres (26.2 feet) at its longest length and 15 metres (49.2 feet) in depth at its deepest point. The larger lake is 35 metres (114.8 feet) at its longest length, and 18 metres (59 feet) at its deepest point.Though the exact depth of the cave is unknown, some speculate that it could be the deepest underwater cave in the world.

Exploring the Cave - Article by Bernd F. Laeschke
“The Italian cave diver Luigi Casati, who is part of an international team of explorers, tries at this moment to prove that the cave is at least 500 meters (1,650 feet) deep. During the first dive, Casati reached a depth of 140 meters (462 feet). He discovered several tunnels that branch off in different directions at a depth of 125 meters (412 feet).Several dives later, Casati reached 205 meters (676 feet), setting a new world record for cold water rebreather cave diving. The total penetration so far has been around 280 meters (924 feet), according to the dive-team.Casati is using Aquatek Voyager rebreathers and a bail-out open circuit decompression line with different gas mixes.At this point, the dives did prove that the Vrelo cave system is the deepest spring in the Balkans. The team, which includes Alan Kovacevic, Alen Milosevic, Alessandro Fantini, JJ Bolanz, Lorenzo Del Veneziano, Luigi Casati, and Tihomir Kovacevic, will continue to explore the cave and hope to penetrate much further.” 

MINA (Macedonian intel news agency) write's on the portal that according to speleologists' assessments, Vrelo's depth is 330m, which makes it the deepest underwater cave in the world, surpassing the Bushman Hole in South Africa that holds the Guinness Record with 282 meters.