According to Screen Daily, Santelmann, who played the lead role in 2012's Kon Tiki, abandoned the role to play Rhesus in Hercules: The Tracian Wars.
Shooting for Northmen, which tells the story of a group of Viking marauders trapped in enemy territory in Scotland, will be take place primarily in South Africa, with some additional shooting in Germany.
Karen Dietrich, the film's producer, told Screen Daily that the film would tell "a timeless story of courage, camaraderie and adventure, with exciting historical roots that have stimulated significant, and ever increasing, interest in the last few years".
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Leonardo diCaprio is reportedly also planning to star in a Viking film, called King Harald, while Lord of the Rings producer Barrie Osbourne was last month in Norway to lobby for government incentives to produce his own viking trilogy.