UTMB will start today, but actually it already started on Monday! They have this little known non-competitive 300 km Bohemian version of the race called Petite Trotte á León.
PTL can be done in teams of two runners only. Basically they just give you the GPS coordinates on Monday and send them off. They can do whatever they like during the week, as long as they go through the control points and finish in 138 hours.
The straightest way will require some steep hard-core climbing, so this event is certainly not for the vertigo-heads like me. There's a team from Finland, but only they know where they are and how they are doing at the moment. I'm sure they will finish in good spirits though, as I met them in Switzerland this summer and they seem like extremely tough guys.