Why is it called the « Diagonale des Fous »?

From south to north, following in the footsteps of the volcanic cirques
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creativecommons

Why is it called the « Diagonale des Fous »?

The Diagonale des Fous crosses Réunion diagonally, from south to north, over 170 km and 10,000 m D+. "Of the Mad", because you have to be. The origin of the mythical nickname on Finishers.