It is described as an ‘elevated hump’ rising to a height of 35 metres (115 feet) with a series of ‘segmented islets’ at its west side.

[4] Seal Island is the remains of a granite inselberg capped by a layer of Bridgewater Formation calcarenite which has been extensively eroded by the action of the sea.

[1] A survey carried out in 1996 reported the following vertebrate animals to be present - Black-faced cormorant, Little penguin, Sooty oystercatcher, Rock parrot, Silver gull and Fairy tern.

The 1996 survey also noted the presence of Galahs and Australian sea lions but assumed these animals were not residents of the island.

[7][8][9] Since 2012, the waters surrounding its shores are part of a sanctuary zone located within the boundaries of the Southern Spencer Gulf Marine Park.