The run starts from the opposite side of the lake and ends in Listvyanka, a town on the shores of the vast water source, 60 km south-east of Irkutsk in Siberia.

Ed Graham: "Looking across Lake Baikal along the marathon path. Shot at sunset the day after the race."

The surface of the frozen lake is peppered with 'hummocks' - small hills of ice rubble.

Lake Baikal, The 'Galapagos of Russia' can be found in south-east Siberia. This 3.15-million-ha lake is the oldest and deepest in the world. It's listed as a UNESCO World Heritage Site, is 25 million years old and contains 20 per cent of the world's total unfrozen freshwater reserve.