The accident happened at about 3:30 p.m. when a large wave swept the women and two men out to sea along Highway 1 in Santa Cruz County.
The women were rescued by a lifeguard and transported to a local hospital where they were pronounced dead.
After being swept into the water, the men made it to a rock where they were rescued by a Coast Guard helicopter. They did not suffer any major injuries.
Officials say the surf was very rough at the time.