Waimea Bay is located on the North Shore of O‘ahu in the Hawaiian Islands at the mouth of the Waimea River. Waimea Valley extends behind Waimea Bay. Waimea means "Red Water" in Hawaiian.

Captain Clerke aboard HMS Resolution stopped at Waimea Bay on 28 February 1779. Clerke had shortly before taken command of the ship after Capt. James Cook was killed at Kealakekua Bay on February 14, and was leaving the islands for the North Pacific. It was the only O‘ahu anchorage which this expedition visited. The site was densely populated at the time, and remains of a heiau (Hawaiian temple) can still be found above the bay.

In winter, Waimea and other North Shore locations such as Pipeline and Sunset Beach host a number of surfing contests because of the large waves found here. These waves are created by winter storms in the North Pacific, and their arrival on O‘ahu's North Shore are typically forecasted accurately several days in advance. In summer, Waimea typically has clear and calm water.

There are other locations named Waimea in the Hawaiian islands.