Flashing across the water at close to 90km/h, the inflatable is urged along by twin 225-horsepower engines. A section of swell looms and well-salted passengers hold on tight, their legs working like shock absorbers as the boat leaps from crest to crest. They don't call this the Aqua Rush Tour for nothing. The ride is taking place in beautiful Shark Bay, off the most westerly point of the Australian mainland.
With its more than 1,500km of coastline, Shark Bay is one of those places that reinvigorates the passion of the world-weary traveller. If you've not visited, imagine a place where sea, sky and desert meet to create a perfect trinity of turquoise, blue and orange.
The folks at Unesco were obviously impressed. In 1991, Shark Bay became one of the few places to be heritage listed under all four of the organisation's 'natural' categories, including for its beauty.
Despite all it has going for it, though, Shark Bay is known primarily for Monkey Mia, the resort town 850km north of Perth where you can feed dolphins.
But there is much more here. Such as the Aqua Rush Tour, for instance. It's not always thrills and spills, though. If the sea is flat it's actually quite a smooth - albeit rapid - ride. And guide Greg Ridgley slows down to take in the sights.
The six-hour tour begins from Denham (the main township, about 30km from Monkey Mia) and heads 18 nautical miles out to Dirk Hartog Island, the northern tip of which saw the first confirmed evidence of a European on Australian soil.
In 1616, Dutchman Dirk Hartog nailed a pewter plate onto a tree saying 'Dirk woz here', or words to that effect, before sailing off. The plate was found 81 years later and taken back to Amsterdam.
The island is home to a wide range of birdlife, including sea eagles and osprey. Ridgley motors the boat slowly along the shoreline to give guests a view of a large sea eagle in its eyrie. The bird eyes the onlookers before lifting off into the sky and returning a few minutes later, clutching a fish in its talons to feed to its young. Later, there will be encounters with dolphins, Pacific gulls, loggerhead turtles, a shovel-nose ray and a southern right whale with its calf.
But the highlight of the tour is the Zuytdorp Cliffs at Steep Point. Several fishermen are dotted along the cliff tops, using helium balloons to lift their lines away from the craggy shoreline, with its five-metre swell.
'Are you all ready to go surfing?' yells Ridgley. Surely he's not serious? He spins the boat around, hits the throttle and rides it up onto a monster swell. It's the biggest wave most of the passengers have seen, let alone ridden, and the feeling of being pushed along by such a beast is mind-blowing.
Hearts still pounding, the group finds a secluded little beach on which to have a cup of tea, a biscuit and a good lie down, before zooming back to Denham. In total, the trip covers some 80 nautical miles (148km), which explains the need for such a fast machine.
You don't need to spend long in Denham to learn that the locals are a little peeved at all the attention Monkey Mia gets in the media. So it was the last straw when an A$8 million (HK$40 million) interpretive centre to celebrate Shark Bay's biodiversity was earmarked for the popular neighbour. Denhamites - the town has 720 permanent residents - dug in their heels and the centre was built in their town instead.
The centre, which opened in March 2006, has a map of the region etched into its polished concrete floor to provide a sense of place, while back-lit display panels illustrate environmental assets, including vast seagrass beds, which, at 4,800 square kilometres, are the largest and richest in the world. These support a huge dugong population and provide food for a multi-tude of fish, which in turn feed the dolphins, sharks and rays. Shark Bay is home to 323 species of fish; 218 bivalve species; 80 coral; seven species of marine animal; 230 species of bird; 37 species of mammal; and 100 species of reptile and frog.
All these facts and figures build up an appetite and many tour groups drop in at the Bay Cafe for a feast of local sand whiting in beer batter.
As galling as it may be for the good folk of Denham, no talk of the area is complete without a mention of Monkey Mia's dolphins. Feeding takes place three times a day, the most popular session being that in the morning. The whole affair is well-governed, with rangers making sure visitors look but don't touch. A few lucky members of the crowd are chosen to hold a fish out but that's as hands-on as it gets. It's still an incredible experience as the dolphins swim up close as you stand in knee-deep water.
These amazing creatures are just one part of this relatively unknown environmental wonderland, which is now protected for generations to come.