How do I reach the first GPS cache I see?

In Tomb Raider, just after you reach the first campsite, there is a GPS cache on a small rock jutting out from the rocky wall.

I've tried jumping to this ledge, from every angle I can think of, to no avail. I know there's something up there. It glows yellow in my Survival Instincts. I just can't get to it.

How do I reach this GPS cache?