Marcus Thompson hadn't thought about holding his breath as a party trick to win free drinks, but as New Zealand recordholder with a time of 6m 42s it would be a mean trick.

Thompson has just set the time for "static apnoea", adding 31s to the previous record for lying face-down on the bottom of a swimming pool.

That seems unlikely to qualify as an enthralling spectator sport, but "No Bubbles", the local group who compete for pool and freedive records, can boast eight hard-core members.

Thompson also holds records for "dynamic apnoea", the distance covered underwater. He has covered 107m without fins and 124m with the one fin competitors use.

At 31, he has a background in swimming but did not get into the weirder world of diving to blackout point until he came to live in New Zealand four years ago.

Thompson has a New Zealand mother but was born in London. After completing a teaching degree, he travelled, becoming interested in snorkelling and then freediving while living in Istanbul, Turkey.

He has since spent time in Milwaukee in the American Mid-West and in Bangkok, Thailand, before bringing his unusual accent and his wife, Hilary, to live in Auckland.

At the teams world championships in Vancouver in August, the cold, dark water suited the Kiwi team but not other competitors used to the clear, warm water of the Mediterranean or the tropics.

Thompson finished in 20th place with a depth of 41m - the winners were pushing 70m.

The New Zealanders train in Lake Pupuke on the North Shore. They swim out to the middle, drop a line 60m to the bottom and dive in the murk. "It takes some getting used to," Thompson said, "but now I love it. When we get good conditions it makes it easy."

The sport was about controlling fear, confronting your demons and overcoming them. "It makes me build character."

He set his static record at the West Wave pool in Henderson, with cameras filming.

"It was horrible. I've done that lots of times in training but with people watching and expectation on you it's much harder.

"But I wanted to get familiar with that, because that's what it's like in competition overseas."

The No Bubbles divers train twice a week at a Panmure pool, in Lake Pupuke when they can, with occasional trips to more pleasant spots such as the Poor Knights Islands.

The aim is to learn to relax body and mind and allow the "mammalian dive reflex" to take over.

The reflex is the body's natural reaction to being underwater, with the heart rate slowing and blood being shifted to the heart and brain.

Thompson is yet to have any blackouts but they are not uncommon among competitors.

Even more common is doing the "samba" - the inability to control the shaking of muscles and sometimes to stand up after deep-diving. Loss of muscle control causes disqualification in competition.

Thompson does not worry about doing himself harm and said the risk of death was minimal.

It's a sport in which experience counts and age doesn't seem to be a bar, as most of the records are held by people getting into their 30s.

Thompson aims to represent New Zealand at the next world individual championships in Switzerland (pool) and the south of France (freediving) next year.