Kiwi free diver Ant Williams breaks world record for deepest ice dive

New Zealand-born free diver Ant Williams has broken the world record for the deepest dive under ice in Norway.

Overseen by Guinness World Records, Williams swam down 70m below the ice to beat the previous world record by 5m.

The 47-year-old, who now resides in Australia, trained for months beforehand, including trips to Finland and Lake Taupo.

His team had to dig two metres of snow, before sawing a hole in the frozen surface of a Norwegian fjord. Then lower a rope down into the impenetrable blackness before he could dive down.

Then with nothing more than a wetsuit, goggles, a nose clip and a torch, Williams swam into darkness.

At this time of year, temperatures in northern Norway can drop into the negatives.

Williams said he had some challenges but was ecstatic to enter the record books.

"It feels fantastic to have finally achieved this radical goal," Williams said on his Facebook page.

"It didn't fall easy though. It was a super challenging dive. The brutal cold and the darkness were far beyond anything I have experienced in the sport. It was a relief to be back at the surface.

"I felt relaxed on the way down, but the swim up was tough going. I think I was over-weighted and when my dive response kicked in at depth my legs felt like lead.

"It took me nearly 30 seconds longer than normal to swim up. This is common with no warm-up diving when you don't get a dive response before your deepest dive."

Williams has been free diving for nearly 20 years and can hold his breath underwater for eight minutes.