The Site comprises a large proportion of the Western Port embayment, some 60 kilometres southeast of Melbourne, and contains extensive intertidal mudflats, mangroves, coastal saltmarshes and seagrass beds. It is an internationally significant feeding and roosting area for numerous species of summering waders. A total of 115 waterbird species has been recorded within the Site, including more than 35 listed under international migratory bird agreements. Notable species include the curlew sandpiper (Calidris ferruginea) and the eastern curlew (Numenius madagascariensis), both listed as vulnerable internationally and critically endangered nationally. Another outstanding feature of the Site is its high diversity of ghost shrimp, including the locally endemic Michelea microphylla. The seagrass beds provide important breeding and nursery habitat for a range of fish species. In recent years, the mean numbers of ducks and large wading waterbirds have declined, probably due to drought conditions in the region. Additional threats include invasive non-native species, impacts of recreational activities, and pollution from surrounding agricultural and urban areas.