One of the places that we tried to visit on the route south from Perth to Margaret River was the Busselton Jetty. This is the longest wooden jetty in the southern hemisphere, stretching out about 2 km into the ocean. And on the day we arrived it was grey, raining and the underwater observatory at the end of the pier was closed due to poor visibility. So all we ended up getting was a look at a wet, wooden structure stretching off to the horizon. Oh, and this look out tower, and the sign for the platform alongside the rail line that runs down the Jetty.
Frankly I found the Jetty to be a singularly unfriendly place, with poor signage to get you there and staff who seem to be impatient with you for turning up in the rain. I'm sure that the Jetty is a fine work of engineering, but I'm not much interested in returning any time soon.