OAHU, HAWAII—Unusually strong sea swells off the coast of Oahu’s North Shore have exposed more than 70 petroglyphs carved into the lava rock along Pupukea Beach for the first time since 2010. Many of the images depict human-shaped figures and dogs. According to Western Digs, scholars think the petroglyphs may have been used to document travel, to mark trails and boundaries, and to commemorate important events.