Our rented Hyundai valiantly negotiated the rocky road with the spirit, if not capability, of a Land Rover. Slowly, we lurched up the uneven track until we spied the tell-tale column of rocks. Clambering out, we headed into the sweet-scented pine woods, where the only sign of human life was the small silver buckets left to collect the sap that would flavour future bottles of retsina.

Our rented Hyundai valiantly negotiated the rocky road with the spirit, if not capability, of a Land Rover. Slowly, we lurched up the uneven track until we spied the tell-tale column of rocks. Clambering out, we headed into the sweet-scented pine woods, where the only sign of human life was the small silver buckets left to collect the sap that would flavour future bottles of retsina.

Pine needles cushioned our steps as we wended our way through the cool, shadowy woods, and then a burst of blinding sunlight broke through the branches. Framed by the trees, the bright white cross of a small church stood out against a clear azure sky. We had reached our destination - the serenely simple 12th-century stone church of Agii Anargiri, and its more recent whitewashed counterpart. Peering through the windows of the two little churches we could see ornate icons, the sombre faces of saints encased in silver marked with the kisses of hundreds of worshippers, candelabras and small devotional offerings.

But no man-made creation, however devotedly crafted, could match the beauty of the setting - the churches were perched on cliffs above an emerald bay. In splendid solitude - silent but for the chirping cicadas - we sat beside the old church bell and gazed down upon red rocks topped with lush vegetation descending to multicoloured pebble beaches bordering glittering seas. The speck of a sailing boat on the horizon was the only visual confirmation that we were not the last people on earth.

Yet this was no venture into the unknown, no voyage of discovery, but simply a last-minute package holiday to Greece - to the island of Alonissos, to be precise. For the fourth year running, the land of myths and mezes has seen tourism drop. Hit by competition from Eastern Europe, unprecedented bargains and last-minute deals abound. It was with some trepidation that I had returned to Greece. My last trip - to report on the juvenile debauchery in the Rhodes resort of Faliraki - had left a sour stench in the nostrils. But those in the know assured me that there were islands still untouched by all-you-can-drink offers, and Alonissos was a prime example.

The fickle finger of environmental fate has spared the most northerly of the verdant Sporades islands from being overrun by high-rise apartments and clubbers. Once renowned for its wine, the island's vineyards were killed off by disease in 1952, and many of its inhabitants deserted it. An earthquake 13 years later saw an even greater migration to the mainland. Today, its population of 2,000 is still vastly outnumbered by goats. Though it swells in the summer with tourists, many of whom are Greek, you can still find a quiet cove to yourself. Just 12 miles by two, the island is so small that locals hand-draw maps for visitors. Apart from its one remarkably punctual bus, transport is provided by four taxis and a handful of boats.

Unassuming and relatively undiscovered, it has the distinction of lying in the middle of the country's only marine park, thanks to the endangered Monachus monachus (monk seal) that inhabits its waters. Home to the largest colony (approximately 250) of these rarest of European mammals, the waters around Alonissos were granted protected status in 1992. The result is seas so clear that even the water in the harbour of the small capital of Patitiri looks like a tropical-fish tank. With hunting banned and fishing restricted, the island boasts 300 species of fish and 80 different types of birds, including the rare Audouin's Gull and Eleonora's Falcon, as well as dolphins and whales.

Travelling to Alonissos is a simple affair, but apparently just tricky enough to deter the masses. While many tourists opt to remain on Skiathos, where the plane touches down, we boarded the efficient Flying Dolphins hydrofoil. Just over an hour later we arrived at the small port of Patitiri. There used to be a one-way system in the island's capital, and its two roads are nicknamed "up" and "down" street. But the locals simply ignored the arrangement and it was quietly forgotten.

Alonissos, in the words of one local expat, is "the island they leave alone". Created when an earthquake devastated the old hilltop capital of Alonissos village, or Hora, Patitiri does not have the charm of some Greek villages. But, with its buildings now encased in vines and bougainvillaea, it is a pretty working port hemmed in by cliffs with some intriguing shops. Venturing skywards we reached the old town, a collection of renovated traditional buildings that cling to the side of the hill. Down a maze of cobbled alleyways we found art galleries and tavernas, each with a view more spectacular than the last. We settled for one in which a group of pensioners was enjoying a liquid lunch punctuated by bursts of song and dance.

At sunset a golden glow descended as we drank palatable plonk or frappés, and contemplated the distant silhouettes of islands as they slipped into the shadows. But at night we retreated to the small harbour town of Steni Vala, where luxury sailboats are moored next to fishing vessels. It boasts a handful of homely tavernas with menus that consist of whatever the owner has caught that day. Nightly we went through the ritual of admiring the day's sea bream or red snapper before it was placed on the scales for pricing. As we supped wine to the sound of lapping water, melt-in-the-mouth calamari, juicy lobster and feta cheese pies were served next to plates of tzatziki and crimson tomato salads.

Most of the inhabitants of Alonissos live in the south-east of the island. The west coast remains a rocky paradise, while, bar the Gerakas marine research station and a few herders' homes, the north appears almost deserted. In spring and autumn it is a haven for walkers. Just minutes from the main road you can stroll down into valleys resplendent with herbs andtrees overburdened with figs, walnuts, almonds and olives.

But when the water is so clear, the countless small beaches tucked away in coves around the island prove irresistible. Daily we tripped and slid our way downward through olive groves to find a new bay. We snorkelled around the rocks, admiring the display of marine life around us. For those in search of even more seclusion, Alonissos is surrounded by six islands and 22 islets. A couple such as Piperi, where the monk seals are most prevalent, and Gioura are now off-limits and most are uninhabited. A group of houses on Peristera are the homes of archaeologists working on a newly discovered ancient shipwreck. Some Orthodox monks still inhabit the post-Byzantine monastery on Kyra Panagia.

On our return trip from the monastery, Pakis Athanassiou leant over the side of his sailing boat and eyed the southern edge of Alonissos. An eccentric, headmaster-like figure who was instrumental in setting up the marine park, he recalled a time when he played among the vineyards as a child. Despite being the owner of the island's oldest tour operator, Ikos Travel, he stared with contempt at the new buildings the locals hope will attract more visitors. With a mournful sigh and a tragic expression worthy of Sophocles, he pointed to a cluster of whitewashed buildings amid the green of the island and berated his countrymen. "Look. Where there were once only olive trees, now there are buildings," he said. "The Greeks, they love to ruin Greece."

Perhaps. But, if that is the case, so far they have been unsuccessful.

TRAVELLER'S GUIDE

To reach Alonissos you fly to Skiathos where you transfer to the hydrofoil or ferry to Patitiri. Terri Judd travelled with Laskarina Holidays (01444 880380; www.laskarina.co.uk). For departures in May, one week at the Villa Aphrodite in the old village costs from £340 each based on three people sharing, while a week at the Maria Studios in Votsi costs from £390 each based on two sharing. Laskarina and many other operators have a range of packages available to other Greek islands for departures in the next few weeks, though the range of possibilities dwindles during October.