Montanero is exactly right and it is now true confession time for ol' Hikermor.
Last month I was out on Santa Rosa Island, one of the Channel Islands, which I had first seen in 1982, and an island on which I have spent extensive time since, doing archaeology and some paleontology. I and two companions were checking out reports of paleo material about three miles from the road.
Returning, I started back before my buddies, since I am hiking slower and slower these days. To make a long story short, I became confused and was headed in the wrong direction, about 90 degrees off course, when my companions caught up with me and steered me straight.
What happened?
I had a map, but it was tucked away in my pack - never referenced. - wrong!
I had spent time on the island, but this was my first time in this area (SRI is a really big island - 53,000 acres, with lots to see).
Pretty easy to get complacent if you're been on the island a bit, even if not in that area. Always wise to confirm position!
I also had allowed myself to become a bit dehydrated. This is unforgivable. I know much better, but the water was stowed in my pack and I was trying not to slow the group too much.
Ah, the insidious foe- dehydration! When exerting oneself it's easy to go through a lot more water than you'd think. I began my adventure with two full liter Nalgenes and wound up drinking them both (save a bit I used to extinguish my small fire).
I'm glad it worked out okay!