Clew Bay (/ˈkluː/; Irish: Cuan Mó) is a natural ocean bay in County Mayo, Republic of Ireland. It contains Ireland's best example of sunken drumlins. The bay is overlooked by Croagh Patrick to the south and the Nephin Range mountains of North Mayo. Clare Island guards the entrance of the bay. From the southwest part of the bay eastwards are Louisburgh, Lecanvey, Murrisk, and Westport; north of Westport is Newport, and westwards from there lies Mulranny, gateway to Achill. From the south side of the bay, between Clare Island and Achill, can be seen.