Sligo Bay (Irish: Cuan Shligigh) is a natural ocean bay in County Sligo, Republic of Ireland.

Sligo Bay is opened between Aughris Head (South side) and Roskeeragh Point (North). The inner part of the bay is divided into three smaller bodies of water, hosting the estuaries of three rivers: Drumcliff, Garavogue and Bonet. The river Garavogue reaches the bay in its central part, named Sligo Harbour, which is divided from the outer part of the bay by three small islands: Coney, Oyster and Maguins. On the southern branch of Sligo Bay also has its mouth the Ballisodare River, near the village of the same name.

The bay is characterised by the peninsulas jutting out into it, which create vast areas of sandy beach at low tide, along with the tidal islands which are only accessible at low tide. The notable landforms within the bay and its peninsulas are:

• Maugherow Peninsula
• Rosses Point Peninsula
• Coolera Peninsula
• Oyster Island
• Coney Island
• Maguins Island

Large beaches and tidal plains located around the bay are a good habitat for shellfish. This kind of food attracted settlers since the Stone Age, as demonstrated by a number of middens discovered in the area by archeologists.

During the centuries in waters of the bay occurred several shipwrecks. Quite well studied is the wreck of Labia (25 September 1588), a 728-ton Venetian ship. Shipwrecks became almost common during the following centuries and their number started to decrease with the decline of the port of Sligo in the 20th century.

Sligo Airport is located on the bay's shore, at the foot of Knocknarea, a hill which overlooks the peninsula between Sligo Harbour and Ballysadare Bay (Bonet estuary).

There are four lighthouses in Sligo Bay.

The 25m high Blackrock lighthouse 54°18′28″N 8°37′4″W / 54.30778°N 8.61778°W / 54.30778; -8.61778 in Sligo Bay is notable for having external steps until halfway up the tower.

Sligo Bay hosts three lighthouses near Rosses Point, the Metal Man, Lower Rosses and Oyster Island lighthouses.

Sligo Bay is concerned by the Donegal to Mayo section of the Wild Atlantic Way.

Ballysadare Bay hosts a well known seal colony.

The estuaries area is protected under European legislation being listed as a NATURA 2000 site; it is also a Natural Heritage Area, defined and managed by the Irish National Parks & Wildlife Service.

• Wild Atlantic Way

• INFOMAR page on Sligo Bay (Geological Survey of Ireland)