A minor dilema

How do I keep the map dry? If it were a single sheet it wouldn't be a problem. I'd simply keep it in a plastic sleeve of some kind. But it's folded concertina fashion, which means I'll have to turn the "page" every two kilometres or so. Even if I find somewhere dry to take it out of the plastic and do this, my hands will be wet and eventually the map will get soaked. Then again, maybe it won't rain and this will be academic.

Distance walked today: 3km
Total distance walked since blog began: 217.2km
Days left until launch of Kisokaido Project: 104