Kauai (also known as The Garden Island) is an island on the planet Earth, part of the nation-state of Hawaii and the northernmost island of Hawaii's archipelago. Kauai is a beautiful location, attracting many tourists to such attractions as Ka'a Beach.
By the 23rd century, the Kauai government had taken steps to ensure that the beauty of the island's locations would remain unspoiled and natural. Kauai's capital was Lihue, the location of a shuttle field. Spock visited Kauai for a ten-day shore leave near Ka'a Beach in 2253, but was called away after four days, departing from the Lihue shuttle field. (TOS novel: Vulcan's Glory)