Wailua (literally, "two waters" in Hawaiian[2]) is a census-designated place (CDP) in Kauaʻi County, Hawaiʻi, United States.

Inland Wailua is often referred to as a bedroom community, since it is home to many, but lacks any commercial or government facilities.

Coastal Wailua is a significant commercial center, with many hotels and condominiums for visitors.

The Wailua River is the only navigable river in the state of Hawaiʻi and is a center of activity for locals (water skiing, kayaking) and visitors (boat tour of Fern Grotto).

23.8% of all households were made up of individuals, and 8.1% had someone living alone who was 65 years of age or older.