The trick with Spanish Bottom is to arrive just as the jetboats make their pickups and before any backpackers can get down off the rim. The Cataract Canyon warning sign and river register are on shore just behind the jetboat. Can cause some hard feelings to sign up for campsites as requested, and then find a solo backpacker in a spot reserved for ten boaters. But then, they don't have access to the register (located at big rock just below the sign).