Siberian Ice Marathon (January)
The start line is in Omsk, where winter temperatures can plummet to -39C. All the participants are given warm hats.
Marathon des Sables (April)
The world’s hottest ultramarathon. Runners must carry all their food and gear, and put their feet in plastic bags. Temperatures can reach 49C. Six marathons in a week. The longest single stage is more than 50 miles.
The Comrades Marathon (May)
The world’s oldest ultramarathon, first run in 1921 to commemorate South African soldiers killed during the First World War. It’s 56 miles either from Durban to Pietermaritzburg, or in the opposite