A sturdy but friendly looking little wooden ship, Gerda III was built in 1928 in Denmark to service lighthouses. She faithfully carried out her mission of shuttling crew and supplies back and forth to a single lighthouse in the Baltic Sea for many years, but in 1943 she was given a job of life-saving importance: help a fleet of other Danish ships rescue nearly 8,000 Danish Jews from Hitler’s Final Solution.

It was September 1943 when a German official warned the Danish government that Jews residing in Denmark would be rounded up and then shipped off to German death camps. In October 1943, an underground fleet of a few hundred small vessels was assembled to secretly ferry Danish Jews to Sweden.

According to the Mystic Seaport Museum, 22-year-old Henny Sinding and a crew of four hid 10 to 15 people at a time in Gerda III’s cargo hold. They’d pilot the boat as if they were making supply trips to the lighthouse, but would detour at the last minute and head toward nearby Swedish waters. Though she was boarded many times by German officers, her human cargo was never discovered. This video from the Mystic Seaport Museum has more on Gerda III’s storied history.

The operation saved 96 percent of Denmark’s Jewish population from certain death in only one month. Gerda III was eventually donated to the Museum of Jewish Heritage in New York, but today she is in the care of the Mystic Seaport Museum in Mystic, Connecticut. The museum currently is treating Gerda III to a full restoration.