From running for roughly 251km on hot desert sand to sledding across the Alaskan wilderness, people around the world put themselves through some incredibly difficult challenges. Image Credit: Unsplash/Silas Baisch

How much difficulty can you handle, and what obstacles would you endure to win?

Click start to play today’s Spell It, where we narrow down some of the toughest endurance challenges on Earth for you to be ‘aware’ of.

Human beings are no strangers to competition. The most daring, however, take on impossible feats, like racing on hot sand and risking being attacked by anacondas. Here are some of the most gruelling endurance competitions on Earth, according to a March 2023 report in the National Geographic:

1. Marathon de Sables, Morocco

The US-based Discovery Channel called this race the most difficult footrace in the world. It’s because at the Marathon de Sables, contestants have to run for approximately 251km – much of it over hot sand. First held in 1986, this ultra-marathon occurs in the Morocco segment of the Sahara Desert. Racers are expected to be self-sufficient, and responsible for their food, water and supplies, as they race to survive the six-day event. With temperatures that frequently exceed 40 degrees Celsius, the Marathon de Sables is as much of a test of mental fortitude as it is of physical endurance.

2. Iditarod Trail, Alaska

This annual sled dog race is held across 1,609km of Alaskan wilderness, through blizzards and whiteouts. Temperatures usually hit below -50 degrees Celsius as man and dog follow the route of the Great 1925 Serum Run to Nome – a moment in time when diphtheria threatened Alaskan natives, causing 20 brave mushers and 150 dogs to deliver critical medicine across 1,084km. The race is held in memory of that event, and more than 50 mushers enter each year.

3. Jungle Marathon, Brazil

When running this 254km course in the Amazon rainforest, contestants have to be prepared. They could encounter anacondas in ponds, piranhas in rivers and even jaguars in trees. Add to that, the climate – at nearly 40 degrees Celsius and 99 per cent humidity, racers are at constant risk of overheating and need to keep an eye on both speed and safety. Having to grapple with swamps, river crossings, steep inclines, dangerous climbs and narrow trails, it’s no wonder roughly 25 per cent of contestants drop out before reaching the end of the race.

What do you think of these difficult endurance tests? Play today’s Spell It and tell us at