The Towers at Santa Cruz mark one of the dive sites on the southeast side of the island. They were associated with the Santa Cruz Acoustic Range Facility (SCARF), which determined the sound profiles of US submarines during the cold war. That work continues, but has moved to quieter waters in Alaska, since those days. So far as I know, the facility is only as a landmark now, for hikers and divers. It lends its name to the divesite below, just west of Yellowbanks.