Williamstown Harbour sits on the eastern shore of Lough Derg in County Clare, connected by road through the townland of Drumaan East near the village of Whitegate.

The harbour has historically served as a notable point of access to the lough, and the area retains the remnants of a historic steamboat quay and an associated hotel.

The site has been home to Castle Line Cruisers, and land in the vicinity is zoned for water access to Lough Derg. Nearby Dromaan Harbour also provides public access along this stretch of shoreline.