Sure, there are also a number of cold water long distance swims - the English channel is famous, the Tasmanian ones less so .. but they're cold, long, and have some wicked currents depending which one you take.

* https://www.iswimhappy.com/tas

* https://www.derwentriverbigswim.com/

The Rottnest swim is just a long warm bath for those that like to dip a toe in and start easy.

To the best of my knowledge few ever attempt the horizontal falls even at slack tide - the waters are warm but the salties and the sharks can be off putting .. come tide change the stoppers will eat people.

> than the water off the coast of Australia.

I should note that Australia is a large continent with an area equal to that of mainland contiguous USofA .. it's not all Gold Coast Qld, just as the US is not all Florida.

Eg: the current water tempreture in San Francisco ( 12.5°C / 54.5°F ) is on par with the September water tempreture when surfing offshore breaks in southern Western Australia (not Perth, the south coast where all the fun is).