I believe that they are 'set-up' to a certain degree.
The contestants will have been briefed on what to expect,and will have also taken a somewhat 'truncated' survival course.
Once they have been placed in the 'situation', it's down to them how they implement what they have been taught.
It is totally impossible to fore-see how things will work out between the contestants and the 'situation',and in order to cover themselves legally,the programming people HAVE TO have some sort of rescue plan or medical e-vac system in place before they allow the contestants to hit shore,or even leave the boat.
These shows are more 'reality' based than most,but they are still heavily over seen,because the risk of fatal injury or death is more 'odds-on' than not.
The programmers would not leave themselves open to judicial prosecution ,which would be the result should a contestant die due to their non-diligence
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