Reminds me of a time doing field work on the Channel islands - we parked the car up high and our plan was to descend 300 feet or so to the coast, work along the coast and then climb back to the vehicle - all cross country, no trails involved. The fog was rolling in, with no signs of clearing and I thought "It might be hard to find a white vehicle in the fog", so I took coordinates.

Very glad that I did, because we were less than 50 yards from the car before it became evident in the thick surrounding mist. After that, I almost always took coordinates, especially when parked in a featureless situation.