I ween lost at sea in the middle of the ent on a semi-survival trip on the remote corral ring of Clipperton in dec 2011/Jan 2012. Nobody should go out without one. In my case the ring is 7 miles round. Water on both side and I could not get lost. But I could have been lost on the Sea of Cortez during the 5 day trip on a small trwaler. Also, to find stars for orientation, grid references from a documented topographic point, one needs a compass. Plan A, B and C...and low tech should always be A.