Between ad 1000 and 1050 the communities living around the Roskilde Fjord deliberately scuppered a large number of wooden ships to create a barrier across the mouth of the fjord and thereby help protect their settlements from raiders. In 1962 the National Museum of Denmark mounted an ambitious underwater excavation to recover waterlogged remains of these Viking vessels. A coffer‐dam was built and a large number of timbers raised and subsequently preserved. A number of reconstructed ships are now displayed in the Roskilde Ship Museum, including a knarr (long‐distance sea‐going cargo vessel propelled by a sail), an oar‐propelled merchant ship, a warship similar in form to those depicted on the Bayeux tapestry, a ferry or fishing boat 12 m long, and a Viking longship of the type that would have been crewed by 40 to 50 men.
O. Olsen, 1990, Five Viking ships from Roskilde Fjord. Roskilde: Viking Ship Museum