An island 6 km west of Bai Chay, connected to the mainland by causeway and developed as a resort and marina complex. Most of the quality cruise operators depart from Tuan Chau Marina rather than the older Bai Chay pier, as it has better facilities and less congestion. If you're joining a cruise, you'll likely start here.
The island itself has a small beach, an amusement park, and various resort hotels. None of it is especially worth your time beyond the marina. The Aquarium of Tuan Chau has a modest collection of local marine life and is adequate entertainment if you're killing time before boarding.