We made two trips — one on a Melbourne Cup Day holiday and one while we were living in Perth. Every guide says to go to Rottnest Island, and the guides are right.
It is a park with little development and the primary transport is bike or hop-on/hop-off bus. We took a ferry and rented a bike (same service) — about a 30-minute ferry ride. In addition to the beaches and snorkeling, an attraction is the Quokkas — a rat-like creature that is not scared of people and will come up and eat out of your hand. We only ended up seeing them at a food place — they are nocturnal and most of them are apparently asleep during the day.
We had a cool partly cloudy day and it was still a great ride around the island — probably 25 miles with some stops for hikes down to beaches. It was the best beach bike ride I have ever been on. At one of the points, we saw whales migrating by. Spent most of the day there and light rain started as we headed on the ferry home. Definitely have to go back on a sunny day — the clarity of the water and the white sand create a bright blue even in clouds, but when the sun is out it is almost glowing.
"The best beach bike ride I have ever been on. When the sun is out the water is almost glowing."
Our second trip to Rottnest was as "locals" — we walked to the ferry at Elizabeth Quay (which took us down the Swan River to Fremantle where we picked up the Freo passengers) and this trip was focused on snorkeling. But similar to our first trip, we had overcast weather and a threat of rain.
Without a bike, you take hop-on/hop-off buses around the island. If they ran to their timetables it would be great, but twice we were waiting over 30 minutes. The three primary areas to snorkel are Parker Point (too windy on this trip), Little Salmon Bay (was OK), and The Basin. Still only saw silver, white, and black fish — no brightly coloured fish.
We finished off the day at Pinky's Beach — in tribute to an old resort from the 1920s — and had a couple of Quokkas lurking around. Harmless and friendly as they have no predators on the island. On the way home, we sampled two of the local Western Australia beers on the boat ride back. Not my favourites.