The vivid, intense blues of Sydney Harbour, reflecting the delicately cloud-dotted sky above it, looked like someone had applied some Photoshop filter to real life. The sun danced off the waves, refracting diamonds across kilometres of water.

Ferrys, yachts and kayaks skittered across its surface, while gentle waves lapped at the white-gold sand of the harbour beaches. Trains and cars hummed across the bridge, and tourists filled their camera memories, trying to find the best selfie.

Below the surface, life was different, the keels of the boats and the pylons supporting the piers not even nibbling at the edges of the activity beneath and beyond.

The Sydney Harbour bunyip was the largest in Australia, naturally. Their home is the largest of the waterways. Rivers are funny, you see, they split into segments, you can’t have one bunyip for the whole length of the Murray, for example, too much travel, and bunyips are home bodies.

This bunyip has no name, although the People Remaining do know of it. It doesn’t require one, it simply is. It is old, and has little time for, or interest in, the fleeting scurries of the world above the waves.

It took offence at the appearance of the Japanese mini-subs during World War II. One was taken care of by the above-water creatures, one they claimed to take care of, and one disappeared. Of course, those below know what truly happened. It is not a good idea to poke a bunyip.

The builders of the Sydney Harbour Tunnel had paid enough attention to things unsaid by people who don’t get involved. The bunyip found that project amusing and in the years since, has occasionally nosed across the top of the structure, feeling the strange sounds and vibrations from the machines within.