The Vendée Globe sees competitors take part in a gruelling 24,000 mile (39,000km) sailing race around the world.
They have to sail completely on their own and get by on only short bursts of sleep.
Fewer than 100 people have ever completed the challenge.
The tough conditions are likely to have an impact on the sailors’ mental health, so competitor Pip Hare is taking some tech with her that’s designed to monitor how she feels.
Zoe Kleinman finds out more for BBC Click.
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