FORTUNE -- When James Cameron was about 14, he embarked on his first underwater mission. Well, not Cameron so much as his mouse. He put it in his homemade submersible and watched it sink to all of four or five feet into Chippawa Creek, in the Canadian suburbs of Niagara Falls. The mouse survived, so the missions got bigger and bolder. Last year, Cameron, 58, became the first-ever solo explorer to touch the bottom of the Pacific Ocean at the Challenger Deep in the Mariana Trench, the deepest surface on Earth. Since then, he has done something possibly more extraordinary: Earlier this week, he donated the submersible and all the related technology to Woods Hole Oceanographic Institution, a private research operation in Cape Cod, where he will also join its Board of Directors and a new robotics team.
Cameron's move is a rare one. While the frontiers of exploration have been carried out largely in the private sector over the past decade -- Richard Branson's Virgin Atlantic, Elon Musk's Space X, and the like -- the machines and technologies involved are often billionaire playthings, shrouded in mystery and intellectual property rights. The moneyed moguls themselves have tended to be less than civic-minded with their toys. After Steve Fossett became the first person to circumnavigate the world by balloon, in 2002, he donated his capsule to the National Air & Space Museum, where it has been on display since. He did not give it to meteorologists to dissect.
In prepping for his deep-sea dive, Cameron did a test run of sorts at the New Britain Trench, in the Solomon Islands of Papua New Guinea. He was amazed at how little scientific data there was on the trench. "We're always talking about space," he said recently at a meeting of the Explorers Club in New York, "and I loved sci-fi and I thought space was it too. But there's an alien world right here on Earth, in the oceans." Cameron drove home the point: "We say we've been to the bottom of the ocean. But that's like parachuting into a cornfield in Nebraska at midnight, walking around for a few hours with a flashlight, and saying you've explored America. We need more."
Cameron's submersible, the Deepsea Challenger, is valued at around $100 million, much of which Cameron paid for out-of-pocket. It is the kind of devotion to brand-new gadgetry that is virtually nonexistent in academic and publicly funded circles. By contrast, ALVIN, researchers' go-to deep-sea submersible, was decommissioned for a refit in 2010 after five decades in the field. "It's like adding a jet engine to a propeller fleet," said Andy Bowen, Woods Hole's director of its National Deep Submergence Facility.
The Deepsea Challenger dove to approximately 10,900 meters; current standard-issue research equipment can only go to 6,500 or 7,000 meters, Bowen said. "It'll help us transform from a Lewis & Clark approach to one of holistic, constant observation," he added. Agreeing with Cameron's cornfield quip, Bowen said, "So much of what we've done has just been Sputnik stuff, showing off for that moment, for the bragging rights. But it didn't really yield good scientific data."
Bowen said that already he was planning on using some of the Deepsea Challenger's technology on existing missions in coming weeks. But, he noted, "how it's going to help explore the ocean is really a work in progress at this point, to be frank." When federal scientists work with a submersible designed for human occupancy, such as the three-person ALVIN, it requires strict certification. Cameron's device operated outside of that bureaucracy, meaning it's uncertified technology. "This is a prototype," said Susan Avery, the president of Woods Hole. "It will take a lot of work to take it from what it is to what we want it to be, which is a practical workhorse."
Avery was quick to point out, though, that "this kind of public-private partnership is the new normal. It's a wonderful opportunity. But there are also not many other opportunities."
In the age when America's space shuttles are all mothballed in museums while other nations boast of plans to head to the Moon or to Mars, Cameron's ocean deal provides cold comfort. Even the mega-rich have needed help of their own; Fossett's capsule, Air & Space dutifully notes, is officially called The Bud Light Spirit of Freedom.