Kailua () is a census-designated place (CDP) in Honolulu County, Hawaii, United States. It lies in the Koolaupoko District of the island of Oahu on the windward coast at Kailua Bay. It is in the judicial district and the ahupua'a named Ko'olaupoko. It is northeast of Honolulu – over Nu‘uanu Pali. In the Hawaiian language Kailua means "two seas" or "two currents", a contraction of the words kai (meaning "sea" or "sea water") and elua (meaning "two"); it is so named because of the two former fishponds in the district (Kawainui and Kaelepulu) or the two currents that 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. In 2017 census, the population had dropped to 38,000. The population was 40,514 at the 2020 census. Places of note in Kailua include Kailua Beach Park, Kaōhao or Lanikai Beach, Kawainui Marsh, Maunawili Falls, and Marine Corps Base Hawaii. It was home to Barack Obama’s winter White House. History Early history 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. After the Oʻahu army's defeat by King Kamehameha the Great at the Battle of Nuʻuanu in 1795, the political capital and residential seat of the aliʻi nui of Oʻahu was relocated from Kailua to Honolulu. Beach Kailua Beach is crescent-shaped, about long, and ranging between wide. The ocean bottom fronting the beach slopes gently to overhead depths without any coral heads. Light to medium waves support surfing and bodysurfing. The steady trade winds make Kailua Beach a top windsurfing and kitesurfing destination. Robby Naish, first World Champion of windsurfing and Professional Windsurfers Association Hall of Fame inductee, grew up in Kailua. Sea kayaking and stand-up paddleboarding to the protected seabird sanctuaries Flat Island and the Nā Mokulua, popularly known as "the Mokes", have become increasingly popular water activities at the beach. Geography Kailua is located at (21.397370, −157.739515). Nearby towns include Kāneohe, Maunawili, and Waimānalo. According to the United States Census Bureau, the CDP has an area of , of which is land and (26.62%) is water. A significant portion of the water area is Kawainui Marsh, the largest wetland in