The Tunnels of Tarcoola is set in a real place, the Sydney suburb of Balmain. Sometimes I mention places in Balmain such as the main road, Darling Street, and Elkington Park. Readers have asked me where they can find other places in the book, especially the old house, Tarcoola.

The answer, I'm afraid, is that there is no Tarcoola. I made it up. There are a few houses scattered around Balmain that inspired Tarcoola, but it's not really any of these.

Below you'll find a couple of maps of the Balmain in the story, showing where everything is. The contours of the land are real, but most of the important places in the book are made up.

This is a map of Tarcoola and its surroundings above the ground

This is a map showing what's under Tarcoola. The map that Martin draws in the book is much better than this!

I have also been asked, initially by the editors, how the Doughnut and the cave below it could have been full of water some of the time, and empty at low tide. To satify myself that this could happen I drew a few diagrams, and you can see them below. I hope they make sense.

This is a cross-section showing the beach, the Doughnut and the tunnel at high tide

This shows the beach, the Doughnut and the tunnel at a normal low tide

This shows the very low tide that occurs at the start of the book

This shows where the tide was when David made his memorable swim