I vaguely remember there's a science fiction story about an underwater civilization where the buoyant force servers like gravity for us. Since the force points outwards, for that civilization, the planet is "up above" their head and the space is "down below".

What a humourus coincidence that it was in Australia the upside-down walking beetle was found.

There are other insects (and common outside Australia) that do this: Specifically, water boatmen which live underwater and have little legs that they use to push themselves around with. This includes the "lesser boatman", Corixidae and Pleidae, and the "greater boatman", Notonectidae.

In particular, Notonecta glauca (or common backswimmer) swims on its back and will walk under the water surface searching for prey: https://www.researchgate.net/figure/Lateral-view-on-the-wate....

A beetle? In my aquarium I have snails walking upside down under the water surface!

Australia is the most appropriate place for such findings.

Down under, really?

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How is this a story. I've seen this myself.

Yep, aquatic beetles are able to do this, and snails do it all the time. Is a well known fact.

as it walking using surface tension it is somewhat like a space worker using magnet boots.

We noticed a month ago a few water snails crawling upside down the water surface.

This reminded me about "How can the Bumblebee fly even though it's not aerodynamically capable of doing so? Because no one told it about this limitation". Upon some search, for an accurate quote, I learned that this is a myth, and that Bumblebee flight does not violate the laws of physics [0]

[0] http://www.todayifoundout.com/index.php/2013/08/bumblebee-fl...