In 1845, Sir John Franklin set sail from England with two ships, more than 100 crew members, and three years’ worth of provisions, hoping to locate the northwest passage in the Canadian Arctic. Instead, the ships and everyone on them disappeared—seemingly without a trace.

It took more than 10 years and many rescue expeditions for British officials to piece together what had happened: After the sea froze around the ships and Captain Franklin died suddenly in June 1847, the expedition members decided that their best chance of survival was to trek hundreds of miles across the frozen ground in search of civilization. As far as we know, none of them survived.

The fate of the ships themselves, the HMS Terror and HMS Erebus, remained a mystery for the next century and a half. Finally, in 2014, Inuit and Parks Canada archaeologists found the sunken HMS Erebus in Victoria Strait, and in 2016 an Inuit hunter helped lead searchers to the HMS Terror in Terror Bay off King William Island.

This week, the Canadian government released remarkable underwater video footage of the HMS Terror’s interior, which until now hadn’t been seen by anyone other than the original crew since Queen Victoria was on the throne. Parks Canada, in partnership with the Inuit, obtained the footage as part of what the press release calls “one of the largest, most complex underwater archaeological undertakings in Canadian history.”

They explored more than 90 percent of the ship’s lower deck, including the crew’s living quarters and the captain’s cabin (the captain of the Terror was Franklin's second-in-command, Francis R.M. Crozier). In the video, you can see beds, desks, and shelves stocked with plates, bowls, and glasses. It might seem like water would do some serious damage to the ship and everything in it, but the opposite is actually true in this case—cold temperatures help keep the wreckage in good condition, and the sediment that coats the artifacts creates an environment with less oxygen, which can even preserve organic artifacts like paper.

And Parks Canada does believe there’s a strong possibility of discovering written documents amid the wreckage. Large amounts of sediment seeped through windows near the captain’s cabin, making it the best-preserved area of the lower deck. Thermometers and a tripod were already discovered, but map cabinet drawers and boxes are still unopened, and researchers have yet to enter the captain’s sleeping quarters at all.

Finding any written documents on the ship could dramatically increase our understanding of what happened to the Franklin expedition. So far, only two notes on the same piece of paper have been discovered: One from May 1847 that mentioned all was well, and another from the following spring briefly detailing that Franklin had died and the ships had been deserted. Because of the lack of any logs or journals from the expedition, our knowledge of what happened on the ships is still patchy at best, and we have almost no information on the mental state of the crew members—or an answer to the question of what ultimately drove them to abandon the ships when they should have had plenty of food and supplies in stock.

While you wait for Parks Canada to unlock the mysteries in the captain’s quarters, you can read more about the Franklin Expedition here.