Penguin Island, Marine islet in Rockingham, Australia.

Penguin Island is a marine islet covering about 12.5 hectares with cliffs, small sea caves, and beaches dotted along the shore. A 1.5-kilometer walking trail connects these different areas and includes several viewpoints overlooking the water.

Penguin Island was declared a conservation park in 1918, covering 11 hectares within the Shoalwater Islands Marine Park. In the 1940s the colony was already under pressure: landing parties with guns and dogs, occasional fires and four to five thousand rabbits stripped the vegetation and sped up erosion. Taking a dog onto the island became illegal in 1950, and a baiting programme in 2013 removed black rats that had reduced penguin numbers.

The island's name comes from the little penguins that breed there; the German name Zwergpinguine refers to the same birds. From June to mid-September the island closes during the breeding season, and since 2007 numbers have fallen from about 1,600 to roughly 120 in 2024. Visitors once shot the birds and brought dogs; taking a dog onto the island became illegal in 1950.

A ferry from Mersey Point provides access to the island, with the crossing taking about five minutes. The service operates only during specific daytime hours, so timing your visit accordingly is important.

In 1946 the naturalist Vincent Serventy estimated about 500 breeding pairs here; by 2007 there were 1,600 to 2,000 birds, and by 2022 only about 250. A 2013 baiting programme removed black rats that had reduced the colony.