I also read Nicky Spinks thoughts about this year's Barkleys Maratons race
. A race which no-one finished for a second successive year.
It actually is a bit like orienteering race. Course is not marked. Course goes also off trail. Master map available and runner will draw the course on their map by themselves. There are check points in the forest. On the check points there is a book and runner will take a page from the book as a proof for visiting the check point.
Interesting race and concept. Nothing for me though, but after watching the documentary maybe a regular marathon this year...