David Wilson thumbs his nose at the daddy of all dunes, only to be shown who's boss.
The hard, straight rain slackens off. Cue a muted celebration. Much of the time on this 10-person wilderness tour, we have been stuck glumly chatting while raindrops relentlessly drum the minibus roof.
Now, the weather is grey but good enough to indulge in an adrenaline-charged spot of quad biking or sandboarding at our latest stop, Henty Dunes a white rolling desert amid the lush rainforest of Tasmania's west coast.
Influenced by a story about how heavy-metal fiend Ozzy Osbourne once came to grief on a quad bike, I pick sandboarding, which sounds like a breeze. In theory, you just lie on your front, let go and invite gravity to do the rest. Sweet.
Better yet, Henty Dunes is far less pedestrian than it sounds. The largest moving dune system in Tasmania, Henty consists of acres of white hilly sand reminiscent of the Snowy Mountains.
Before we try to get to grips with the dunes, our guide warns against riding one particularly steep slope, which she says can be dicey. Like the small, forbidden room in the legend of Bluebeard's castle, the deadly dune suddenly becomes a nagging source of fascination.
As we whiz down its minor counterparts with fading fervour, I grow twitchy. After larking around on the middling slopes for a while, I split from the pack and wander off with my board to face the abyss.
Oops! The drop is even more dire than it sounded, provoking paralysis.
But after taking this detour, quitting seems out of the question. Gripping the sides of the board, I eyeball the base of the megadune and lean into the gradient.
Whoosh! Only late in my slide do I realise that because the other dunes plateau conveniently, I have neglected to learn how to brake.
Ramming the base of the dune with a thud and a grunt, I come to a stop and then, still grimly gripping the board, keel sideways, mangling my thumb in the process.
In the throbbing hush that follows, my eyes drink in the mountainous expanse that must now be negotiated the slow way.
My attempt at climbing back fairly murders my muscles. Halfway up, as I frantically gulp some of the world's purest air, I teeter on the brink of quitting but continue on my hands and knees like a lost legionnaire. More than once I collapse, but eventually claw my way to the summit, where, drenched in sweat as the sun takes a dive, I realise I have lost my bearings.
For an eternity, as rain again starts to spit, I criss-cross the moonscape, growing ever more dispirited. Finally, a scout sent from the van sees me and shepherds me back. After a droll welcome, out comes the first-aid kit.
In a kind of consolation, the group's glamour girl coos soothingly as she uncoils and wraps the bandage. Still, my swollen bloody thumb continues to throb like the dying sun until a paracetamol fix wipes away the pain.