The world’s deepest indoor pool is set to open in Poland.
The pool will allow swimmers to dive 45 meters below the surface.
Created as a training site for divers, the pool will hold 8,000 cubic meters of water when completed — that’s 27 times more water than standard 25-meter pools.
And how deep will it be? At a depth of 45m, the pool will be as deep as a 15-story building.
To help free divers to go without their wetsuits water temperature will be warmer than standard pool temperatures.
Water will also be filtered 15 times a day to keep the pool transparent and clean for both divers and outside spectators.
By comparison, traditional pools are filtered an average of three times a day.