I chose GC1ERNF, which is a photo-search through an area where you're allowed to go off the paths. Looked fun enough, and with 7.5 km, quite the ideal distance for us. We were a bit late getting started though, which was also because we had to select an 'optimal' route along all of the points, using Google Maps.
It was cold but nice. At the fishing pond near the parking space we found lots of people ice-skating. They were playing ice hockey, but there were also people just skating in circles for the exercise. And there were people shoving an old TV across the ice... WTF!?
Anyway, further into the nature preserve, we were all alone -- there were no other walkers in sight. The gound had been soggy and muddy, and we would have slipped ankle-deep in the mud if not for the frost. But that didn't mean the going was easy, because the mud had frozen up quite uneven. But it was nice -- the (relative) silence, the frosty landscape, the waypoints... But it was a bit of a pity we had to do one stretch twice (to and back). Guess that couldn't be helped.
But between points D and H, we found out that Google's aerial photos were outdated. Instead of a lake/large pond at the centre of the preserve that we could walk around, the conservation society had cut a canal between the lake and the river. Now I knew where those photos of people wading thigh-deep into the water had come from!
Given the temperatures, we opted to keep all of our clothes on and stay away from the water. And it was getting late too -- by that time it was 15:20, and in one hour it would be sundown. There are few things I dislike more than getting stuck in a nature preserve without any light. (One of those things is getting stuck in a nature preserve without any light while there are semi-wild cattle about -- luckily those had been taken in for the winter in this particular case.)
Grumily, we set off back again, to walk around the lake. But then we discovered that we had enoug information to calculate the longitude of the cache location! I created a waypoint with the correct longitude to the north of the preserve, and one to the south. Then I created a route between the two -- my GPSr then draws a line between the two.
So now we knew that the cache had to be on that line somewhere... Checking the topographical map (again on the GPSr) we selected a likely spot.
After another brisk walk, we had arrived on a position along the line. I aligned myself north, and looked straight ahead -- just as we suspected, there was a spot that could fit the hint straight ahead. As we didn't have to stick to paths, we just cut across the terrain (clambering over a barbed wire fence that had fallen down) and lo and behold: there was the cache!
The cache-layer tried to outsmart us by letting the most obvious route go through the canal so that we had to go around -- but we outsmarted him by deducting the cache location and cutting the route short! We were back at the car at 16:00 sharp, with only 5.8 km on the track-counter. Ha!