A scientist surfaced yesterday after spending almost two weeks under water in a steel box, pedalling a stationary bicycle to generate electricity and growing algae to convert carbon dioxide into oxygen.

Lloyd Godson, a marine biologist, had been five metres (16ft) down on the bottom of a lake near Albury in southeastern Australia since April 5. Before he was hauled up Mr Godson, 29, said: “I will be glad to get out in the sunshine and fresh air again. I have had thoughts of running like Forrest Gump and not stopping.”

Living inside a bright yellow capsule that he called the BioSUB and which measured only 6 sq m (65sq ft), the scientist was on a quest to see whether Man could live under water naturally. He breathed air provided by a coil of algae watered with his own urine and pedalled a bike connected to a generator to produce electricity.

For drinking water he relied upon technology that extracts and condenses vapour in air.

Regular deliveries of food by divers supplemented his natural underwater diet of dried algae because his support team worried that he would be overcome by indigestion had he existed on algae alone. Funding for the project came after he won an adventure proposal competition run by the Australian Geographic magazine.

Mr Godson said of his adventure: “It starts to play on your mind a bit, after 12 days, obviously. You start to get a bit of cabin fever but I handled it surprisingly well. I thought it was going to drive me a bit more nuts than it did.”

Of the significance of his feat, he said: “It’s the first time this has been done, so it’s paving the way for future experiments in this area such as plant-based life support systems for underwater or space applications.

“We got some good data down there so it will be interesting when we analyse all that and the right people see it, and we’ll work on making improvements for the next one.”

He has now been invited by Nasa to take part in an underwater habitat project in 2009.

Mr Godson entertained himself by playing his drums at all hours. He was also able to communicate using both the internet and a video intercom system. “At times it has been stressful, but more just exhausting from talking all day to [website] visitors,” he said. “I expected solitude and got the opposite.”

According to his website (www.biosub.com.au) the television programme Science Shack,on BBC One, built a similar capsule in an earlier attempt to establish the possibility of humans living naturally underwater. The experiment lasted an hour but used simple technology to produce oxygen successfully under water.

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