GULF OF MAINE – The end for the steamship Portland came after hours of darkness. The ship succumbed to 100 mph winds and 60-foot waves that reached above its twin smokestacks and pounded them into the sea.

A century later, a wreck that left no survivors and remained cloaked for decades on the floor of the Atlantic is still tantalizing researchers with questions about its last moments.

Last week, scientists completed the first in-depth exploration of the wreck since the Portland’s location in the Stellwagen Bank National Marine Sanctuary was confirmed last August.

The November 1898 shipwreck killed 192 and remains the worst maritime disaster in New England history, though relatively little is known about it.

“You’ve got a history book with the pages torn out,” said Bruce Terrell, an archaeologist with the National Oceanic and Atmospheric Administration. “We’re looking to fill them in.”

The Portland set sail from Boston on Nov. 26, 1898, primarily carrying Mainers returning to Portland after Thanksgiving.

The forecast predicted stormy weather, but the 290-foot ship set off on its 100-mile journey anyway.

It wasn’t long before the Portland was in serious trouble. Two storm systems collided, forming a devastating gale that destroyed boats and homes up and down the New England coast and took 500 lives.

The destruction of the luxury steamship shook area residents, and it was later referred to as “New England’s Titanic.” But the secrets of the ship’s final moments remained a mystery, despite numerous attempts to unlock them.

Researchers John Fish and Arnold Carr finally discovered the wreck by tracing the trail of debris and bodies to a site between Gloucester and Provincetown, some 460 feet below the surface.

A glance at the wreck all but discounted a theory that it went down after a collision – there wasn’t enough damage. Its location boosted reports that the Portland hugged Boston’s North Shore before attempting a turnaround about 14 miles off Gloucester.

A legendary sighting off Cape Cod, in which the vessel supposedly sounded “four short horn blasts” in distress, couldn’t have happened, even though the story later inspired a book title. The Portland was found too far away.

The ship’s exact location in the 842-square-mile sanctuary has been kept secret to discourage plunderers, but exploring the Portland isn’t easy, even for those who know where it is.

On Tuesday, an underwater research robot got stuck in a pipe that snapped its lights off. During last year’s expedition to confirm the Portland’s location, the robot was snared by stray fishing nets that drape the wreckage.

“[The site’s] got some serious problems,” acknowledged Ivar Babb, a University of Connecticut biologist who teamed with National Marine Sanctuary researchers on the project.

Despite the difficulties, last week’s expedition yielded some results. Two protrusions thought to be the ship’s twin smokestacks turned out to be their cast iron bases. That strengthened a theory that the boat was downed by a tremendous wave that wiped out its top two decks along with the stacks, Terrell said.

Exactly how the boat got into a position to be blasted by the wave is still unknown.

Babb believes a lack of damage to a rod connected to the ship’s side paddlewheels shows it was not directly hit by the wave. Terrell disagrees, and says he thinks a paddlewheel was knocked out of whack by the wave.

Babb’s theory could indicate that Capt. Hollis Blanchard accidentally exposed the ship to the wave. Terrell believes the boat was so seriously damaged that Blanchard had no control over it. Blanchard’s reputation is at stake.

The expedition’s lead investigator, Ben Cowie-Haskell, said no one will ever really know why the captain ignored the forecasts. But it’s still important to learn as much as possible about what led this spot of ocean to become a mass grave, he said.

Scientists said the quarters of the Portland’s mostly black crew are of particular interest. Among those killed were 30 to 40 blacks, making the wreck a huge loss for Portland’s growing black community.

The quarters, still believed to be intact in the bow, could yield important information about how the community lived in the late 19th century, Terrell said.

Researchers also are pursuing National Landmark status for the site, which Cowie-Haskell said would come with prestige that could help protect it.

The Gulf of Maine was relatively calm Tuesday, its swells languidly rocking the research boat and turning alternately gray and deep blue to reflect the sky.

But what Terrell calls the “karmic dent” left by scores of deaths at the site is still apparent to him. The victims were just ordinary people, he said. But they got caught in a terror he can still feel at the site 105 years later.

“You can sort of feel that abandonment of hope, that abandonment to the sea,” he said.