San Diego police were searching the area for clues to who planted the razor blades near Bonita Cove.
No one was reported injured.
The same type of booby-trapping was reported on Aug. 10 when a 41-year-old woman cut her foot on a razor blade near a playground in Mission Bay, San Diego lifeguards said. Nearly a dozen razor blades were discovered pushed into the grassy ground, sharp side up.
No suspects were identified.