Travelers are voting Rottnest Island as the best island near Perth. There is 1 island near Mandurah a city just 40 km from Perth. The most popular of these is Penguin Island near Mandurah. You can find 29 islands near Western Australia and 150 islands in the country of Australia. Our members favorite in Western Australia is Seal Island and Green Island is the top pick in Australia. Want more? Check out our map of islands near Perth.