Fabien Cousteau, the grandson of legendary French oceanographer Jacques Cousteau, emerged from the deep Wednesday after 31 days in an undersea lab off the Florida Keys.

The 46-year-old Cousteau - whose efforts bested a 30-day mark set by his grandfather a half-century ago - and his ‘Mission 31’ returned to Islamorada at about 10am. His team cheered and greeted him with hugs at the coastal Florida International University facility that operates the bus-sized Aquarius Reef Base undersea research laboratory, the only one of its kind and located 20 meters (65 feet) below the surface.

‘This has been a monumental success on multiple levels,’ Cousteau told a press conference. Cousteau said he was ‘elated’ about the quality of the work, but ‘exhausted’ from spending more than a month under water, where his team carried out a battery of experiments, some of it streamed live online. ‘We achieved more than we imagined possible,’ he told AFP. ‘The most important thing was reaching the maximum amount of people for 31 days on multiple platforms.’

The goal of the mission launched on June 1 was to observe marine life, the effects of pollution on coral and how long-term underwater stays affect people. Scientists took daily diving trips outside the lab to carry out experiments also focused on climate change and ocean acidification.