Kailua is a city in Hawaiʻi County, Hawaii, United States, in the North Kona District of the Island of Hawaiʻi. The population was 11,975 at the 2010 census, up from 9,870 at the 2000 census. It is the center of commerce and of the tourist industry on West Hawaiʻi. Its post office is designated Kailua-Kona to differentiate it from Kailua located on the windward side of Oʻahu island, and it is sometimes referred to as Kona in everyday speech. The city is served by Kona International Airport, located just to the north in the adjacent Kalaoa CDP. Kailua-Kona was the closest major settlement to the epicenter of the 2006 Kiholo Bay earthquake.