Wrocław Himalaya climber will go underwater

Bogusław Ogrodnik, an inhabitant of Wrocław, has already made an ascent of the Crown of the Earth, that is all summits above 8 thousand meter above the sea level and now he wants to dive in the ocean depth.

In this way he wants to break the Guinness record. He will be the first one who will achieve such a big difference in level. He reached Mount Everest (8848 meter above the sea level) and now he is going 152 meter underwater.
It would give him exactly 9 kilometer of difference in level. Other daredevils were either on the top of the world or underwater. No one has ever joined it together.