(Reuters) - Four-times world champion Rhiannan Iffland and Constantin Popovici took cliff diving to a new extreme when they launched themselves from 120 metres underground in the Salina Turda, one of the world's oldest salt mines in Romania.
In a first-of-its-kind diving feat, the duo jumped from the walls of the cone-shaped mining area into the underground high-salinity lake in the depths of Transylvania.
The water and air temperature at 12 degrees Celsius was the least of their problems when compared to the fast deceleration of the body during the landing phase.
Facing 8-times higher salinity than the Adriatic Sea, the athletes' bodies were decelerated from 85kmph to zero in almost twice the usual speed before hitting the water surface.
These factors took an extra toll on the athletes' fitness along with the fact that they must dive without any natural light.
"We ticked a 'world's first' box today: the first ever underground dive into a salt mine," Iffland said. "It's very dark down in the lake. The water is 17% more dense than seawater, so the impact is different.
"It's actually quite a unique experience to hit the water when it's that salty. It just pushes you straight up to the surface."
The first documented reference of the Turda Salt Mine in one of Romania's oldest settlements dates back to 1271 and was a source of supply until work ceased in 1932.
The mine is now used as a history museum and an underground theme park which attracts around 700,000 visitors per year.
"It's the most outstanding and mentally demanding project I've done in my life," said Bucharest-native Popovici. "I am really proud to be the first Romanian cliff diving in Romania."
(Reporting by Hardik Vyas in Bengaluru; Editing by Christian Radnedge)