In 1958 two Danish frogmen found part of a ship's rib on the bottom of Roskilde Fjord. It turned out to be part of a barrier of five Viking ships sunk in the eleventh century to stop raiders getting up the fjord. By a brilliant feat of excavation these ships have now been lifted and restored. Among them was the first-ever known example of a deep-sea trader, the 'sea-bison,' which made possible the most remarkable feat of colonisation of the Middle Ages, the Norse occupation of Greenland.

Chronicle tells the story of Viking Greenland and the Danish excavation which enables us to know at last what sort of ship those hardy adventurers sailed in.
Written and narrated by Magnus Magnusson
(How they salvaged the Vikings' ocean-striding bison': page 15)