As a great change up from running (and/or a nice compliment to it), cross country skiing in the dark is a blast. For some reason I thought it would be faster than running though. My average speed was 10:13 per mile skiing. I run between 8 and 9 min/mile, depending on the flavor of the day.
There is another nordic skier setting some nice tracks right behind my house on the canal, so I did 4 laps for a fun 6 miles.
I can't get over how fun this is! (I will be paying for it tomorrow though. I hurt in ways I never do after running).