This is Deepspot - soon to be the world's deepest swimming pool.
It is currently being built in Mszczonow, a town nearby to the capital city of Warsaw, and will open to the public later this year.
The pool will be 45m deep at its deepest point, and will be filled with 8,000 cubic metres of water - that's around 27 Olympic-size swimming pools full!
There will also be an underwater tunnel, where people who aren't swimming can view the divers in action without getting wet.
The current record for deepest pool is held by the Y-40 Deep Joy in Italy, which is 42m deep.
However, Deepspot will only hold onto the world title for six months before Blue Abyss is built in Colchester, UK.
Blue Abyss will be a whopping 50m deep, and will even have a model version of the International Space Station to help train astronauts.