Underwater fun at lake Saarijärvi in Vaala, Finland.
In case you`re wondering how this `upside down` idea works, the divers are wearing dry suits (sealed) that are inflated with buoyant air. They are floating to the surface and are bumping up against the surface ice sheet layer, then they’re just spinning upside down and putting their feet against the underside of the ice. So the bouyancy in this scenario becomes “gravity” when they’re upside down. That’s why the bubbles seem to go down and the person filming is also upside down.