The grandson of famed French oceanographer Jacques-Yves Cousteau has spent 31 days underwater. Fabien Cousteau beat the 50-year-old record set in 1963 by his grandfather by just one day.

"The record was never really the focal point. I knew it was a hook, I knew that symbolic one extra day would get people's attention, curiosity at the very least," said Cousteau who is 46-years-old.

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"This has been a monumental success on multiple levels."

Speaking about his late grandfather, Fabien said: "I think what he'd probably be most proud of is that we were able to reach so many people."

His underwater home for a month was an 18-meter long laboratory called the Aquarius Reef Base undersea research laboratory submerged 20 meters near Key Largo in the Florida Keys.

The undersea laboratory Cousteau shared with five other members of "Mission 31" was air conditioned, had wireless Internet access, a shower, a bathroom and six bunks.

The record-breaking team ventured into the sea several times each day to explore marine life and collect samples from coral reefs.

Scientists from the Massachusetts Institute of Technology and Northeastern University rotated through the laboratory habitat to study the impact of changing seas on underwater life.

Cousteau returned to Islamorada, Florida to the cheers and hugs from his team. The Florida International University facility operates the Aquarius Reef Base undersea research laboratory, the only one of its kind.

He said he was exhausted from spending more than a month under water, where his team carried out a range of experiments.

"We achieved more than we imagined possible," he said. "The most important thing was reaching the maximum amount of people for 31 days on multiple platforms."

The goal of the mission launched June 1 was how long-term underwater stays affect people; to observe marine life and the effects of pollution on corals.

Mission 31 was a 31-day, privately funded expedition at Florida International University's Medina Aquarius Reef Base. The habitat lies 63 feet (19 meters) below the surface of the ocean.

Aquarius is the world's only underwater marine laboratory. It measures 43 x 20 x 16.5 feet or 13 x 6 x 5 meters and weighs 81 tons.