Captain Yood sat high on the stern and steered the longtail boat with his foot. As we passed in the lee of yet another island, the ear-splitting noise of the engine bounced back at us off sheer limestone and for a moment we couldn't hear each other speak. And then we moved past gleaming sands fringed by luxuriant forest, the sound softened again but there was still no mistaking our advance; if we'd been trying to creep up on anyone, we were definitely in the wrong kind of boat.
It felt a bit unfortunate to be shattering the peace of the Angthong Marine Park, those 42 pristine knuckles of limestone bristling with lush tropical jungle and strewn across the Gulf of Thailand, about 28km west of the holiday island of Koh Samui. But then we weren't going to be waking anyone up, because only one of the islands - Wua Talap - is officially inhabited. In fact, it was on Wua Talap that we'd come ashore from our speedboat from Koh Samui that morning and hired Captain Yood to show us the crannies of the Marine Park that the normal day-trip traffic would never reach.
Thus it was that we'd been to the Devil's Bridge, startling a basking turtle on the way; that we'd seen the sad-faced Dusky Langurs and the hornbills who lived at the back of the gorgeous beach at Had Tham Ray; that we'd been to the lagoon that partly inspired Alex Garland's book The Beach on the island of Mae Ko; and now Captain Yood was delivering us to our own private swimming pool, a perfectly sheltered little rock-fringed bay where he ran the longtail's bows up onto coral sand in a semi-cave. Our teenagers, Thomas and Rhena, tipped overboard into a limpid sea as clear as a windscreen and so calm it seemed like it could barely summon up the energy to make waves. We could scarcely believe our luck in having all of this to ourselves.
We don't often do exotic holidays in our family, but having a son about to go off to university is something of a landmark moment and we wanted a shared experience that was exotic but in no way difficult or threatening. Thailand was providing just that.
We'd started slowly, in Bangkok, where the mingling of east and west is a strange mixture of the futuristic and the mystical. The Skytrain, the skyscrapers, the huge shopping malls and the new metro represented the forward-thrusting tiger economy, whilst the spirit houses, the street stalls, the food markets and the soaring red- and gold-roofed temples represented the traditional, spiritual Bangkok. It's a place in the midst of furious change, not always appreciated by tourists. This was demonstrated when we enquired about the possibility of visiting a floating market, only to be told by our guide: "We don't have them in Bangkok any more. We have Tesco."
Within a few days we'd visited the main sites, from the Buddha made of more than 5,000kgs of solid gold in Wat Traimit, to the Grand Palace, a whole walled city in itself of temples, pagodas, pavilions and European-style mansions intended for state visitors, and packed with monkey gods, chedis, emerald Buddhas and mythical birds.
All this colour and noise can result in sensory overload, but fortunately there were some delightful places to escape. In the Supatra River House restaurant, for example, a traditional teakwood house on the banks of Bangkok's Chao Phraya river, we had a lunch of soft shell crab and chicken massaman while watching the mayhem as the longtails, the river taxis and the rice barges carve through the floating water hyacinth beyond our window. And on the 26th floor of the Rembrandt Hotel we had a meal in the Rang Mahal, one of Bangkok's best Indian restaurants, savouring the taste of hand-ground spices while looking down over a cityscape patched with the blue rooftop swimming pools, like fragments of sky fallen to the ground.
Our teenagers were initially nervous of Bangkok's frenzied exoticism and wary of the heat and the unfamiliar diet, but their confidence quickly returned. Rhena and her mother visited a fish spa, a new experience which had them shrieking initially as the fish got to work nibbling at the dead skin on their feet, and then cooing over the smoothness of the result. In the weekend market Thomas challenged me to tackle half a dozen dishes from a variety of foodstalls to see who really liked it hot. Fortunately neither of us experienced any serious consequences.
On our last evening in the city we made an excursion to Siam Niramit, a spectacular show of Thai arts and culture. It's where Thai dancing meets Glee - complete with elephants and a river across the stage - and it made a fitting introduction to the next section of our holiday - up to Thailand's northern capital, Chiang Mai.
Chiang Mai is the place to get to grips with traditional Thailand. Unlike Bangkok, it is almost entirely low-rise, and its ancient centre is composed of intimate neighbourhoods with small hotels, markets, restaurants and travel agencies. The city's setting, amid a fertile plain surrounded by rainforest-clad mountains, makes it an excellent starting point for adventures into Thai countryside on bicycles, on foot, on river rafts, and even on the back of an elephant.
So we did a bit of town, and a bit of country. We tried cookery classes at an organic farm amongst the rice paddies. We visited the Patara elephant farm, one of 16 such establishments in the hills that skirt the city, and learned how to be a mahout (elephant handler) for a day. We even rented small motorbikes to explore the hills, returning in the evening to our boutique hotel not far from Chiang Mai's celebrated night market. The latter was a mixture of temporary street stalls and permanent roofed market areas, where stall-holders sold the latest in boho-chic as well as the latest in tribal fashion.
All in all, it was brilliant for teenagers, who weren't so intimidated as they had been in Bangkok. They particularly liked the market and the motorbikes, but Chiang Mai lacked one key ingredient that my daughter particularly craved: sunbathing.
This explains how we headed south again, and finding our own island swimming pools with Captain Yood.
Whereas Bangkok and Chiang Mai had been slices of Thailand going about their daily business, with us tagging along for the ride, the island of Koh Samui lives, eats and breathes tourism. It starts from the moment you touch down at its small, charmingly laid-back airport, where the terminal buildings are little more than thatched huts between the coconut palms.
For our base on the island we side-stepped the biggest resort of Chaweng, which we thought was a bit brash, and chose to stay in neighbouring Lamai instead. The sea was calm, the beach was broad and clean, and Rhena just loved the itinerant food vendors on the sands, particularly the women with the spring rolls and the guy with the fruit cart, who served up slices of fresh pineapple and mango in plastic bags with a little twist of salt. In the evening we watched the beach boys play sepak takraw, a mix between keepy-uppy and volley-ball, played with a light rattan ball and with considerable skill.
It was from Lamai that we arranged the speedboat across to Angthong and the tour with Captain Yood, but we also had excursions closer to home. There was, for example, a Muslim fishing village a couple of miles down the coast from Lamai, and farther south amongst the coconut palms we came across a working monkey, trained to climb the trees and throw the coconuts down. It was happy to pose for photographs on Thomas's shoulder; in fact, they seemed very comfortable in each other's company.
We also visited Wat Kunaram, a gloriously decorative red and gold temple, with satin-robed monks in attendance. The temple's special feature was one of its previous abbots, whose soul may have departed but whose mummified body was still sitting in a glass case in the prayer hall. Bizarrely, he was wearing dark glasses (evidently his eyes were not a pretty sight), and Rhena thought it looked creepy beyond words.
Lamai's shopping and its night market was much more to her liking. Clothing, cosmetics, jewellery, shoes, all seemed incredibly good value - and a real change to the stuff available on the high street back home in Britain. Thomas stocked up with Thai fishermen's trousers and, at just £4 (Dh23) for an hour, none of us could resist a massage on the beach.
It was in the night market that we had some of our best Thai food, from green curry and seafood omelettes to peanut pancakes, deep-fried crab and fresh fish grilled over charcoal. Everything was cooked on demand, the cost was minimal, and the dishes were eaten sitting at communal tables under the stars. It wasn't so bad, agreed the teenagers, living life like a Thai.
If you go
The flight
Return flights with Etihad Airways (www.etihadairways.com) from Abu Dhabi to Bangkok cost from Dh3,600, including taxes.
The stay
Double rooms at Bangkok's riverside Mandarin Oriental (www.mandarinoriental.com; 00 66 2659 9000) cost from Dh1,185 per night. In downtown Chiang Mai, double rooms at the Chedi (www.ghmhotels.com, 00 66 53 253 333) cost from Dh548 per night. In Lamai, the boutique-style Pavilion (www.pavilionsamui.com, 00 66 77 424 030) offers double rooms from Dh530 per night. Prices include taxes.