Competitors, dressed in diving gear and wearing skis, pull themselves along for 10m underwater. Not only that, they're upside down under a sheet of ice.
Whoever makes the distance the fastest is the winner.
Triumphant Jurius Zavadskis completed the distance in just 47 seconds. He said: "It turned out to be very tough because the skis go pretty fast under the ice and you have to keep up with them the whole time."
But there's not exactly a rush for contestants. Jurius only had one other competitor for this world record!