Have you wondered of the world's deepest underwater cave? Do you know where you can explore it? It's in Czech republic, and was recently discovered by a Polish cave diver Polish cave diver Krzysztof Starnawski, who led the expedition. The cave is at least 404 metres (1,325ft) deep, near the eastern town of Hranice.During his dive, he used a remotely underwater robot to reach the deep cave, but the robot could not hit the abyss. 

He has tried this even in earlier year which led him to depression. This abyss have been explored for ages by many of the divers across the globe, and have not come to this point as he told Nationa Geographic. One of the diver reach only 12 meters deeper than the flooded sinkhole. It is also the more difficult to dive into this cave as it has a mud and water temperature of 15C. Due to this it easily damages the equipment under water. Even with the use of a robot they could not reach to the end of this cave.

Previously in 2014, he only reach a depth of 200mts  and found a narrow opening that led to another pitch black tunnel, and reach about 384 mts. He returned back to  Hranická Propast to find that the squeeze passage had crumbled, widening the aperture. This way he was able to get the passages through the passages and reach the the deep meters of the cave and succeded his exploration of the world's deepest underwater cave  On an interview with ABC Austalia, he said "During this push, the most important part of the job was done by the robot". 

The limestone formation seem to cause a lot of trouble down in the water as hot water was saturating with carbon dioxide like volcano and wore off the rock from the bottom, which itches the skin of the team. It's not an easy task for the exploration of this cave, it took him almost years since 1999 to keep trying his efforts into reaching the depths of this cave.