More than ever, explorers are finding a treasure trove of shipwrecks

Some were fabled vessels that have fascinated people for generations, such as Endurance, Ernest Shackleton’s ship that sank in the Antarctic in 1915. Some were common workhorses that faded into the depths, like the Ironton, a barge that was carrying 1,000 tons of grain when it sank in Lake Huron in 1894.

No matter their place in history, more shipwrecks are being found these days than ever before, according to those who work in the rarefied world of deep-sea exploration.

“More are being found, and I also think more people are paying attention,” said James P. Delgado, an underwater archaeologist based in Washington, D.C. He added: “We’re in a transitional phase where the true period of deep-sea and ocean exploration in general is truly beginning.”

So what’s behind the increase?

Experts point to a number of factors. Technology, they say, has made it easier and less expensive to scan the ocean floor, opening up the hunt to amateurs and professionals alike. More people are surveying the ocean for research and commercial ventures. Shipwreck hunters are also looking for wrecks for historical value, rather than for sunken treasure. And climate change has intensified storms and beach erosion, exposing shipwrecks in shallow water.

Underwater robots and new imaging are helping.

Experts agreed that new technology has revolutionized deep-sea exploration.

Free-swimming robots, known as autonomous underwater vehicles, are much more commonplace than they were 20 years ago, and can scan large tracts of the ocean floor without having to be tethered to a research vessel, according to J. Carl Hartsfield, the director and senior program manager of the Oceanographic Systems Laboratory at the Woods Hole Oceanographic Institution in Massachusetts.

Remotely operated vehicles can travel 25 miles under the ice sheet in polar regions, he said. And satellite imagery can detect shipwrecks from plumes of sediment moving around them that are visible from space.

“The technology is more capable and more portable and built on scientists’ budgets,” Hartsfield said, adding: “You can sample larger and larger areas of the ocean per dollar.”

Jeremy Weirich, director of Ocean Exploration at the National Oceanic and Atmospheric Administration, said the expanded use of telepresence systems, which stream images of the ocean floor to anyone with an internet connection, has allowed more people to explore and discover shipwrecks in real time.

And the digitization of archives has made it easier to find and consult historical documents, said David L. Means, a marine scientist and shipwreck explorer.

Climate change is playing a role, experts said, by producing more frequent and powerful storms that have eroded shorelines and churned up sunken vessels.

In late January, for example, several months after Hurricane Fiona battered Canada, a 19thcentury shipwreck washed ashore in the remote Cape Ray section of Newfoundland, causing a stir in the small community of about 250 people.

That kind of discovery may become more commonplace, Delgado said. “As the ocean rises,” he said, “it’s digging things out that have been buried or hidden for more than a century.”

Treasure hunting isn’t what it used to be.

Private treasure hunters still search for shipwrecks, hoping to find sunken gold, coins, or jewels. But their discoveries often become mired in legal battles, and rarely are their claims ever realized, said Deborah N. Carlson, the president of the Institute of Nautical Archaeology, a nonprofit research organization.

She pointed out that underwater archaeologist Peter Throckmorton once called ocean treasure hunting “the world’s worst investment,” and found that it “only benefits promoters and lawyers.”

Private claims to a sunken ship can be contested by nations or insurers. Spain, for example, successfully defended its claim that it maintained ownership of a Spanish frigate that was sunk by the British in 1804 after an American treasure-hunting company found the shipwreck off Portugal in 2007 and took its trove of gold and silver coins to a Florida warehouse.

The UNESCO Convention on the Protection of the Underwater Cultural Heritage, adopted in 2001, sought to protect shipwrecks from looters and said countries should preserve them and other undersea relics “for the benefit of humanity.”

Hartsfield said that if the goal is “to observe and not disturb” a shipwreck, the cost goes down because it doesn’t require anyone to lower a submersible on a winch to pluck items off the ocean floor. Scientists, he said, can just use a video camera to record the artifacts they find.

More are joining in and exploring the ocean depths.

While treasure hunters still ply their trade, they have been joined by more commercial and research ventures that have expanded the realm of deep-sea exploration.

Weirich said that more shipwrecks have been found over the years in large part because of private companies surveying for oil and gas leases, cables, and pipelines.

Phil Hartmeyer, a marine archaeologist at NOAA Ocean Exploration, said that more private research groups are also scanning the ocean floor and helping to move scientists around the world closer toward a goal of mapping the entire seabed by 2030.