Algoa Bay contains six named islands in two groups of three. These islands are of considerable importance as they are the only islands along a 1,777 km stretch of coastline between Cape Agulhas and Inhaca Island in Mozambique. The combined surface area of these islands is said to be 40 ha i.e. 99 acres. 

Close inshore, near the new Ngquru harbour development at Coega, on the north-eastern outskirts of Port Elizabeth, is the St Croix group, consisting of a main island of that name and two lesser islets, Jahleel Island just off the Ngquru breakwater and Brenton Island on the seaward side. The second group consists of Bird, Seal and Stag Islands. All six islands and their adjacent waters are declared nature reserves and form part of the Addo Elephant National Park. The islands are closed to the public.