23. The guestbook cave in San Diego
Hidden in Torrey Pines, there’s a small cave complete with its own guestbook. From the Torrey Pines Gliderport (yeah, that’s a thing), head west from the parking lot over the edge and then head north. If you can see the nudists on Black’s Beach, stay focused. The cliffs are unstable and people have gotten stuck/fallen/died, no joke. Of course, you may get to the cave and find some arse has taken the guestbook, but at least you can say you did it. Oh and go at low tide, for goodness sake.