The vast Amazon Basin has claimed many lives of those intrepid enough to explore the wild jungles of Brazil.
Yet that did not stop 90 competitors - divided into 30 teams of three - from racing around the central Amazon rainforest.
The race was the Red Bull Kirimbawa Amazon, a multi-sport relay of mountain running, mountain biking and kayaking.
Twenty-one of the teams completed the arduous 200km race held in early December around the city of Manaus.
It was the first Kirimbawa - a term used in the local language to refer to "great warrior".
True to the term, it was a battle for every competitor.
Outside of the exertion needed for each leg, the racers had to compete with 90 per cent humidity and temperatures of 36 deg C.
First place went to the Brazilian trio of Roberto Adalto (mountain running), Thiago Aroeira (mountain biking) and Marcelo Lins (kayaking), who completed the race in less than 12 hours under the team name Xingu.
Mountain running is fraught with difficulty at the most basic level - there's the uneven ground, sharp inclines and a high risk of breaks and sprains - and it requires a huge amount of stamina.
The race started at 3am and saw runners complete much of the 50km course in the dark while coping with the energy-sapping temperature and humidity, before handing over for the mountain bike leg.
This made the initial leg all the more treacherous as runners had to negotiate rough and slippery terrain as well as deep water obstacles - all in minimal visibility.
Adalto finished the running leg in seventh position.
Not all of the bike leg was on two wheels.
At points, bikes had to be carried.
Aroeira managed to make up three places during the 86km ride, leaving team Xingu in fourth place going into the third and final leg.
Lins was the hero of the day for Xingu, putting in a powerful performance on the Negro, Solimoes and Amazon rivers to battle his way into first place and sealing victory.
Lins was surprised he did so well.
"I have never done such a long race in my life. I wasn't expecting such a good performance."
For Lins, the race was gruelling in more than one way.
After celebratory hugs with his joyous teammates, Lins admitted with a smile: "My hands hurt so much and I really suffered a lot with the heat, but now I really consider myself a true warrior."
The exertion was not lost on Adalto.
Said the Brazilian: "We all did fine, but Marcelo's stint made the difference.
"What he did here was really amazing."
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