Kailua is a city in Hawai?i County, Hawaii, United States, in the North Kona District of the Island of Hawai?i. 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 Hawai?i. Its post office is designated Kailua-Kona to differentiate it from Kailua located on the windward side of O?ahu 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.