Completely irresponsible hike - Hardergrat - T5

This is a physically intense and extremely exposed hike. You will need to be able to do the 25km/3000up hike within the time from 8:00-17:40. That is when the last train leaves Brienzer Rothorn. All the while, you need to retain complete focus and not set one foot wrong. If you are too slow, you might need to find your own way off the ridge. If you miss the last train, it's a very long way down.

We hike from Interlaken Ost to Brienzer Rothorn.

http://www.hikr.org/tour/post123141.html
https://s.geo.admin.ch/7af75cea02

https://timetable.search.ch/Z%C3%BCrich-HB..Interlaken-Ost?time=06.00&date=Sun+06%2F17%2F2018&toggle=v1
There is an earlier train at 5:19, though I can not catch that. You are free to go earlier, I'll catch up :) or I'll try. We meet in the train. First car in driving direction.

If you want to cheat, you can take the funicular to Harter Kulm and save 700m altitude.

https://timetable.search.ch/Brienz,Rothorn-Kulm..Z%C3%BCrich-HB?time=18.00&date=Sat+06%2F23%2F2018&toggle=v-1

The limit of people is soft. If you can make a convincing argument to me that you are fit enough to finish the hike and experienced enough not to fall to your death I can be negotiated with.

The hike will only take place if it's dry.

Finally and most importantly, let's not forget to have fun.