We have been off the jetty for less than 30 minutes when we see a small pod of humpback whales coming up for air about 50m from our catamaran.
The sun is starting to set on the horizon and in the distance I can see a dorsal fin crest above the waves. A perfect silhouette of spray forms on the skyline and I watch the whales breathlessly for a minute before, as quickly as they appear, they are gone.
Soon after, a pod of dolphins materialises off the bow and they make long figures of eight as if to say "hello". Quietly, I hope it is an omen of good things to come.
Not many people had heard of Ningaloo Reef when I told them I was making a trip here. Some Australians and scuba divers had heard about it, but none had travelled here and I was curious about what I would find.
It is the only large reef in the world found so near the shore that one can swim from the beach to hundreds of schools of fish, stingrays and turtle after turtle.
The 280km stretch of pristine coral hugs the central coast of Western Australia. It is an isolated area 1,250km north of Perth and more than 3,000km south of Darwin, where thousands of kilometres of sweltering red and rocky desert slide coolly into windswept brush and sandy beaches to the sea.
Exmouth, the small, sleepy gateway to the reef, has a year-round population of 2,200 people which swells to about 6,000 during the height of the tourist season from April to October.
Many of the visitors arrive in caravans, having driven thousands of kilometres across empty highways and sunbaked landscapes to get here.
It is partially Ningaloo's remoteness which attracts people to this beautiful, barren coastline. Fewer tourists venture to this part of the country - most foreigners coming to Australia tend to make a beeline for the much larger and better- known Great Barrier Reef on the north-eastern coast.
Ningaloo Reef is a two-hour flight or 14-hour drive north of Perth.
There is not much to see on the drive up, so flying is often the preferred option. From Perth to Exmouth, the main town servicing the reef, Qantas has two flights a day during the week and one flight a day on weekends. A round-trip flight costs about A$460 (S$460).
Sail Ningaloo picks up guests at Exmouth's Learmonth Airport for a two-hour drive south to Coral Bay, where they join the boat.
At 2,300km long, the Great Barrier Reef is the largest reef system in the world, almost 10 times the length of Ningaloo. But Ningaloo being off the beaten track means divers here are not competing for space or wildlife sightings.
Because tourist numbers are lower, the reef remains in top condition. In our three days of snorkelling, we notice only minimal damage and most of it is due to natural causes - strong storms or natural breakage of the coral - rather than human interference.
I am here in June, having hitched a ride aboard the Shore Thing, a 15.5m-long, 8m-wide catamaran owned and operated by eco-tourism company Sail Ningaloo (www.sailningaloo.com.au), which introduced liveaboard sailing trips to the coral coast in 2010.
It is a good time of the year to visit, though July could arguably be better, when two key migratory seasons overlap. Humpback whales spend time here with their calves in July and August and more than 300 whale sharks come to the reef to feed following the coral spawn between April and July.
Fortunately, the whales seem to be early this year and a few of the guests onboard have just come from whale-shark swimming tours in Exmouth. These day-long tours are the most reliable way to see whale sharks because the companies hire pilots to spot them from above and lead the boats in that direction. Tourists can then jump into the water and swim alongside the gentle giants, striped and spotted filter feeders which reach up to 18m in length.
To prevent harm or stress to the sharks, only a handful of companies have the licence to let tourists into the water with them.
Other boats, such as Shore Thing, must stay at least 100m away, so unless a whale shark swims up to me while I am snorkelling, I have a slim chance of seeing one on this trip, and ultimately, I do not.
But there are other equally exciting aquatic animals to see around Ningaloo. Manta rays call the reef home all year round and are especially frequent around Coral Bay, a town about 200km south of Exmouth. Loggerhead, hawksbill and green turtles glide and dart around the coral in abundance and lay their eggs on the shore between November and February.
Notoriously shy dugongs - marine mammals which look like a cross between a walrus and a dolphin - are present, though rarely seen on the reef. One of the world's largest dugong populations thrives in Shark Bay, about 400km south of Coral Bay.
Dolphins and orcas can be seen playing and hunting around the corals' edge, and more than 500 species of fish, 300 types of coral and 600 different molluscs call the reef home. It is no wonder, then, that it is a Unesco World Heritagelisted marine park.
Ningaloo is a fringing reef, which means vast stretches of reef lie only a few hundred metres from the coast. It is the only large reef in the world found so near the shore - less than 100m in some places - that one can swim from the beach to hundreds of schools of fish, stingrays and turtle after turtle. It offers some of the best snorkelling in the world.
I have opted to embrace the reef with a liveaboard option. The five- cabin boat sleeps a maximum of 10 guests. There are four cosy double and king-sized bed cabins, as well as one with twin bunks which has room to climb into bed and little else, a good option for children.
Sail Ningaloo offers three-night and five-night tours of the reef which cost between A$1,700 and A$3,300 a person, including snorkelling and some diving equipment, all meals and non-alcoholic beverages.
There is fresh hot water on board, though guests are asked to restrict themselves to three-minute showers.
There are nine of us on board, plus three crew, so it does occasionally feel like we are bumping into one another. But between the trampoline nets, where guests can rest across the bow, beanbag chairs on deck, a covered dining area and an indoor banquette lounge, there is enough space and everyone is relaxed, comfortable and snug.
Meals onboard are surprisingly wonderful, given the size of the kitchen. Everything is freshly made on the catamaran - Italian pasta salad, spinach and feta pie, roast chicken with preserved lemons, grilled fresh fish and sticky date pudding - all are expertly prepared by the crew.
The skipper David Fleming was a professional chef before he joined Shore Thing and serves one of the best steaks I have eaten, despite, ironically, being a vegan .
We have breakfast every morning around 7.30am, after which we encase ourselves in thin wetsuits before getting into the water for our first dive around 9am.
The water is between 21 and 26 deg C, depending on the season. It is the perfect temperature for swimming, but not warm enough for the growth of the soft, colourful coral you would see at the tropical reefs of Indonesia or Thailand.
Instead, Ningaloo is mostly made of brown and beige hard coral, but they are just as fascinating.
At one of the dive sites, Asho's Gap, we pass over huge heads of cabbage coral, 3 or 4m across. They look like petrified cabbages or roses, with row after row of interlacing and overlapping leaves and petals rising out of the sandy seabed.
The beautiful corals at Asho's Gap also function as cleaning stations, where sharks, rays and turtles go to have parasites cleaned off their bodies by shrimp and other fish.
We complete two dives before lunch and another one or two before dinner.
I am exhausted by the end of the day, but I go on every dive and do not regret a minute of any of them. Every venture into the water is rewarding - there is so much to see.
On one thrilling day, I swim with a manta ray and watch it gracefully fly through the water and turn in barrel rolls while I flip my fins as fast as I can to keep up.
Later, I see a 3m-long tawny nurse shark, spotted grouper and giant loggerhead turtle.
In the evening, while the sun sets over the horizon, we struggle to divide our attention between four humpback whales playing to the left and a large pod of about 20 dolphins just 50m to the right of our boat.
By the end of the trip, I have seen more reef sharks, turtles and fluorescent fish than I can count.
A few of the divers on board tell me Ningaloo offers stiff competition to the Great Barrier Reef on the other side of the country for the number and variety of animals they have seen, all despite the woeful weather.
It is not supposed to rain much on Ningaloo Reef. Rain falls on the rugged landscape only 25 days a year. But it has been cloudy and overcast since we came aboard, and now the storm system which has been brewing over the horizon is upon us, whipping winds, churning waves and covering the coastline in a blanket of gray.
Though the air is warm, the seascape looks harsh. The water - typically calm and a bright Maldivian blue - is choppy, dark and forbidding.
It is a shame, because when the sun does shine briefly through the clouds, I can see how beautiful Ningaloo is meant to be. The water is clear and full of light, the deserted beaches pristine.
The weather is nothing but bad luck, but none of it really matters once my mask is in the water and my snorkel pointed to the sky.
Our skipper David takes us to protected parts of the reef that are less battered by wind and wave and, under the surface, life continues - a stingray rests in the sand, a turtle, two, no, three are pecking at the coral, and iridescent schools of yellowfin tuna and big-eye trevally swim contentedly with the current. The fish do not care that it is raining.
•This trip was sponsored by Sail Ningaloo and Tourism Western Australia.
•Watch the underwater wonders of Ningaloo Reef http://str.sg/Zefw
•This is the last of a four-part Voyages series on the best boat trips in the region.