Cause of death: accident
Natalia Vadimovna Molchanova (Russian: Наталья Вадимовна Молчанова; 8 May 1962 – 2 August 2015) was a Russian champion freediver, multiple world record holder, and the former president of the Russian Free Dive Federation. Described as "possibly the world’s greatest freediver," Molchanova set an unparalleled standard in the sport. She believed, “Freediving is not only a sport, it is a way to understand who you are,” reflecting her deep connection to the sport. Throughout her career, she achieved 42 world records and earned 22 world championship medals, 19 of which were gold.
Source : Wikipedia