I asked the same questions about one year ago, just before I left for Bonaire and my first shore diving experience. Until then, I had only dived from boats. I was apprehensive about shore diving, especially navigation. But what I found was that diving in Bonaire couldn't be easier. Although a compass could help, we found we didn't need it. We'd walk into the water, dive down following the slope of the reef to some depth we had decided upon, find a distinguishable coral head or something else at that depth that we would hopefully notice on our way back, and then turn left or right--there was rarely any detectable current--and followed the reef. We'd swim for around 30 mins or until air indicated we should turn around, and make our way back. Once we'd swum maybe 20 mins., we started looking for our coral head marker at the depth noted. If we found it, then a compass reading wasn't usually necessary, since we just turned 90 degrees and followed the slope of the reef up--the direction "toward shore" was usually easy to discern. We usually popped up pretty close to our entry point. On occasions when we failed to find our marker, we gave it a few more minutes then turned toward shore. We rarely found ourselves far from the entry point even when we felt we might be. I suppose taking a compass reading and paying more attention to the surroundings would have made our exit even more accurate, but in the end it seemed that my pre-trip concerns had been excessive.