Located within the City of Warrnambool in western Victoria, Merri Marine Sanctuary (29 hectares) stretches from Thunder Point in the west to Breakwater Rock in the east. It abuts a coastal reserve and surrounds Middle and Merri Islands, with Pickering Point a prominent headland. 

Sea life here prospers in the cold, crystal-clear, oxygen-charged waters of the Southern Ocean. Rock platforms are covered in algae while numerous sea snails cling tightly to the rocks to avoid being washed into the sea by the strong waves.  The seabed at the river mouth is a mixture of reef and sand, providing a range of habitats that support diverse marine life.

Two islands, Middle and Merri, sit just offshore, the remains of an ancient sand dune  built up thousands of years ago.  The canyon between the islands is packed with sea life with kelps swaying with the waves, colourful sponges beneath the overhangs, and protected Rock Lobsters hiding in the crevices.

The main habitats protected by the sanctuary include soft sediments made predominantly of fine sand, intertidal and subtidal reefs made of calcarenite, and the water column. 

The intertidal soft sediments are an important feeding and roosting habitat for shorebirds with beach-washed materials on the sandy beaches contributing to the detrital cycle that nourishes many of the invertebrates, such as bivalves, living in the sand. 

Subtidal reefs are the dominant marine habitat and are either patchy and interspersed with areas of sand, or more consolidated hard reef cut by deeper depressions and large crevices. These support extensive kelp forests which provide a rich habitat to explore for snorkelers and divers. 

Merri Marine Sanctuary’s beaches are popular for swimming, and walking tracks along the foreshore lead to points of interest.