Sea-sickness tablets swallowed; waterproofs on. We stumble into a glorified dinghy, straddle an inflatable bench and cling on for dear life. 'Everyone ready?' asks Skipper. Well, no. Not really. Then we're off, accelerating from 0-to-50 knots as fast as you can scream: 'SOS!'
Twenty minutes later, the boat is tossing around black Atlantic waves and the island is a green smudge on the horizon.
Locals call it 'Green Island', but it's actually Sao Miguel and is the largest and most populous of the nine Azorean Islands.
It's somewhere north-east of Bermuda, west of Lisbon, too eastern to squeeze on a North American map, and probably too far into the Atlantic to appear on a European one (even though the Azores is technically a Portuguese archipelago) - and four hours by plane from London.
Until the early 15th century - when Portuguese f amilies emigrated there with sheep and goats in tow - Sao Miguel was a Robinson Crusoe-type outpost. Early sailors en route to the New World used it as a stepping stone, but today its population is 140,000 - plus one cow to every person.
I'd never heard of it, but I still signed up for a riding holiday in the Azores. It is also a whale-watching hub - which is why I ended up bobbing on a motorised dinghy with 14 excited whale-watchers and an awful lot of sea-sickness.
First, Skipper doled out anatomical diagrams of whales (to distinguish a blue from a beaked, for example) and said we 'might' see one.
He didn’t warn us about the spray that would blast our faces, how our bottoms would ache as the boat mounted each colossal swell, or how our eyes would level with the waves one second, clouds the next.
My 60- something neighbour clutches his stomach. “Are you okay?” asks Skipper. “No, I'm not,” comes the reply.
Then, half-an-hour out, some of us find our sea legs. The radio crackles, Skipper swerves left, then stops. “Over there! Whale!” Twelve heads turn (all except two sickly men). I look, too. Surely no whale can be worth the nausea?
Thirty-five yards from the boat is a waterfall of spray. Then a hulk of smooth grey blubber breaks the surface. Adrenaline pumps. You can hear involuntary gushes and sighs. “Wow!” I breathe, in spite of myself. It is worth it.
This is the first of three taking encounters with mother and calf sperm whales off the coast of Sao Miguel - and the beginning of a love affair with an island that seems never to have grown up.
Picture the Scottish Highlands, wind back the clock 70 years, warm the temperature to 20c and you're starting to get the feel for time-warped Sao Miguel.
Narrow paths weave between wildflower fields and stone ruins of what were once chocolate-box houses. Tea plantations of orange pekoe (an aromatic black tea) sprawl over hills - they also grow pineapples and sugar beet.
Farmers (more than half the population works the land) drag hand-operated milking machines after cows, while less wealthy goat farmers live in corrugated metal shacks in fields.
The air is thick with the smell of eucalyptus. Which all begins to explain why Sao Miguel is best explored lazily on horseback.
I was staying at Quinta da Terca, a guesthouse-stable with 33 horses in Livramento, a foresty parish in Sao Miguel's capital, Ponta Delgada. Horses and holiday-makers are paired carefully by Swedish owner Christina de Laval, who doubles as head chef.
Meals are good quality rustic fare: spiced broths, exquisite steak au poivre and cinnamon tarts for supper; frittatas and rainbow-bright salads for lunch, served in a converted stable with vintage car memorabilia tacked to the walls.
Fifteen hours of horseriding are programmed into my week. My seven fellow holidaymakers, all hardened riders, are partnered with nimble horses while, as a novice (I'd never even sat on a horse before), I am given chubby, docile Chicco.
After learning to tack up (clumsily) and balance (precariously) on Chicco, we follow guide Lise to Mata Santa (Holy Wood), named after an old woman who is said to have fled here to escape her violent husband, and survived on vegetation, while concocting love potions from plants.
Lise points out her tomb surrounded by wild red peonies. I try not to topple off Chicco.
By day six, wobbling becomes trotting. I'm partnered with leaner, speedier Thor, and Lise thinks I'm ready to canter.
'Why is he named after the God of Thunder?' I ask. She grins. I cling on to Thor's mane, position my legs and yell: 'Gallop!'
Three gallops later, I'm ready to join the other holidaymakers for a day-long hack in Sete Cidades, an area defined by a huge volcanic crater, with twin turquoise lakes at its centre. A photograph of the view here is what inspired my trip.
The ride stretches around the cliffs, down to the lake where lunch is served on tables set with flowers.
Between rides, tour guide Ricardo shuttles me to landmarks such as Furnas Valley, a volcanic crater with bubbling hot springs, and a botanical garden with a huge thermal mud-brown spring.
At lunch we sample cozido, a local casserole made by steaming vegetables (yams, carrots, cabbage) and meat (chicken, beef, blood sausage) in huge earthen pots underground for seven hours. Some apparently say the eggy sulphur smell lingers, but I found cozido delicious.
Final stop is Nossa Senhora da Paz, a tiny whitewashed chapel perched atop a hill, reached by a tiled staircase.
The story goes that when an earthquake destroyed nearby Vila Franca do Campo in 1522, all that was left of the church was a tiny Virgin Mary doll, which is enshrined in a cabinet outside this chapel.
From here, the view is endless turquoise Atlantic. Half of you wants to shout from the hilltops, but the other half wants to keep this secret Peter Pan island just that.
If You Go...
IN THE SADDLE (01299 272 997, inthesaddle.com) has seven nights at Quinta da Terca from £814pp taking the Learn To Ride Week programme. Price includes transfers, full-board accommodation, drinks with dinner, 15 hours of riding tuition and non-riding excursions (sata.pt). Flights from London Gat-wick to Ponta Delguda from £293. Whale-watching (bluetalassa.com). - Daily Mail