Kailua is a census-designated place (CDP) in Honolulu County, Hawaii, United States. It lies in the Koʻolaupoko District of the island of Oʻahu on the windward coast at Kailua Bay. It is in the judicial district and the ahupua'a named Ko'olaupoko. It is 12 miles (19 km) northeast of Honolulu – over Nu‘uanu Pali. The population was 38,635 at the 2010 census.
In the Hawaiian language Kailua means "two seas" or "two currents", a contraction of the words kai (meaning "sea" or "sea water") and ʻelua (meaning "two"); it is so named because of the two former fishponds in the district (Kawainui and Kaʻelepulu) or the two currents which run through Kailua Bay.
Kailua is primarily a residential community, with a centralized commercial district along Kailua Road. The population was 50,000 in 1992. As of the 2017 census, the population has dropped to 38,000.
Places of note in Kailua include Kailua Beach Park, Kaʻōhao or Lanikai Beach, Kawainui Marsh, Maunawili Falls, and Marine Corps Base Hawaii. It was home to Barack Obama’s winter White House.
During the reign of King Kākuhihewa and his successors, Kanekapu, Kahoowaha, Kauakahiakahoowaha, and Kualiʻi, Kailua replaced Waikiki as the residential seat of the Oʻahu Rulers (aliʻi nui of Oʻahu). Many ancient temple ruins, such as those at Ulupo Heiau State Historic Site, are in the area.
Kailua Beach is crescent-shaped, about 2.5 miles (4.0 km) long, and ranging between 50 and 150 feet (15 and 46 m) wide.