They travelled from Oxford via Switzerland to Venice, through Turkey, Persia and Afghanistan, surviving sandstorms, floods, motorcycle accidents, and time spent in jail.
Severin and his guides rode camels through the Deh Bakri pass to identify the Persian "apples of Paradise" and the hidden hot springs described by Polo.
On May 17, 1976, Severin and his crew (George Maloney, Arthur Magan, Tróndur Patursson) sailed from Dingle Peninsula, County Kerry[8] on the Brendan, and, over more than 13 months, travelled 4,500 miles (7,200 km), arriving at Canada on June 26, 1977, landing on Peckford Island, Newfoundland, before being towed to Musgrave Harbour by the Canadian Coast Guard.
Severin told reporters, "We've proved that a leather boat can cross the North Atlantic by a route that few modern yachtsmen would attempt.".
After three years of researching the legend and early Arab and Persian sketches of medieval ships, he brought the project to Sur, Oman in 1980.
Sponsored by Qaboos bin Said al Said, Sultan of Oman, he guided Omani shipwrights in the construction of the "Sohar", an 87-foot (26.5 m) replica of a ninth-century, lateen-rigged, cotton-sailed Arab dhow.
The epic poem Argonautica, first written down by Apollonius of Rhodes in Alexandria in the late 3rd century BC, became the basis for Severin's next expedition.
Master shipwright Vasilis Delimitros of Spetses hand built a 54-foot (16.5 m) replica of a Bronze Age galley based on a scale model of the Argo.
Along the way, Severin made tentative or conclusive identifications of The land of the Lotus-eaters, King Nestor's palace, the Halls of Hades, the Roving Rocks, Scylla and Charybdis, and also the sirens.
Nine hundred years after the First Crusade, Tim Severin and Sarah Dormon set out on horseback to follow the 2500 mile route of Duke Godfrey of Boullion and other Crusaders from Belgium to Jerusalem, travelling through the modern lands of Germany, Austria, Hungary, Yugoslavia (itself today consigned to history), Bulgaria, Turkey and Syria.
While still a student at the University of Oxford, Severin wrote his thesis on the first European travellers in Central Asia during the thirteenth and fourteenth centuries.
With this background, to commemorate the 800th birthday of Genghis Khan he rode with Mongol herdsmen along the route once used by couriers of the Mongolian empire, mingled with camel herders in the Gobi Desert, and ate with Kazakhs in their yurts.
Ancient Chinese texts tell the story of Hsu Fu, a navigator and explorer sent by the first Emperor of China, Qin Shi Huang, in 218 BC into the "Eastern Ocean" in search of life-prolonging drugs.