James Cameron successfully completed his submarine excursion to Mariana’s Trench, the deepest and most unknown place on Earth earlier today. The descent took roughly two and a half hours, Cameron spent about three hours conducting the first manned scientific exploration of Challenger Deep. For his return trip, Cameron experienced a faster-than-expected, roughly 70-minute ascent, which he described as a “heckuva ride.” Bobbing in the open ocean, his custom-designed sub, the DEEPSEA CHALLENGER, was spotted by helicopter and plucked from the Pacific by a research ship’s crane. The expedition was designed so that Cameron could spend up to six hours collecting samples and video at the bottom of the trench. But his mission was cut short due in part to a hydraulic fluid leak that coated the window of the sub’s “pilot sphere,” obscuring his view. ”I lost hydraulics toward the latter part of dive, and I was unable to use the manipulator arm,” Cameron said this morning during a post-dive press conference held aboard the Octopus, a yacht owned by Microsoft co-founderPaul Allen, a longtime Cameron friend. (Allen was on the scene for the historic dive and posted live updates of the event on Twitter from aboard his yacht, which provided backup support for the mission.) Considering the daunting task of sending humans into the deep, such technical glitches are to be expected, Cameron emphasized: “It’s a prototype vehicle, so it’s gonna take time to iron out the bugs. The important thing is that we have a vehicle that’s a robust platform—it gets us there safely, the lights work, the cameras work, and hopefully next time the hydraulics will work. To read the full story be sure to visit National Geographic.