Take the Green Tunnelbana westbound towards Åkeshov or Hässelby Strand, take off at Abrahamsberg. Follow half-arrows to the On-Inn.
There will be a runners' trail (about 7,5km) and a walkers' trail, with a possibility for a swim stop if you're quick enough. Bring your torches (pannlampa), it is getting dark in the night. No spikes needed yet, though :).
Please order your food at the restaurant before the run. Neither of the hares have a car, so if someone could bring one that would be great.