We found that the anchorage at San Marcial in 2017 was a much more heavily-visited destination than it had been the last time we'd anchored there in 2009. That is fine; people should get to see the classic-yet-somewhat-secluded example of Baja boating that San Marcial offers.
San Marcial has much reefy goodness encircling its northeastern point, plus some other submerged rocky shallows a few dozen yards off the point to the south. Conservative cruisers like us approach San Marcial well off the point and enter the anchorage to the south of the southernmost reef complex; this approach is very safe and well-described in all the most popular cruising guides of the area. Unfortunately, at some time in the recent past someone got the bright idea to plot a shortcut that goes tightly around San Marcial's rocky northeastern point in a relatively narrow passage of deeper water between the reefs surrounding the point and the submerged reefs further off the point. (The map on the right shows the point in question, next to a tiny red dot you can only see if you click on the image to enlarge it. Anyway.) It seems that the GPS waypoints for this shortcut have been shared among many, many cruisers. Heck; at anchor in San Marcial on January 31, 2017, we saw two different inbound sailboats use this shortcut within a period of less than two hours. See that low line of exposed rock extending out to the right past the rounded edge of San Marcial's point, in the left side of that photo up there? Yeah, the shortcut guides boats into the anchorage skimming right past there.