Below the boat’s bow, the water glows a deep and translucent blue. The anchorchain arcs down into it, through shafts of sunlight, to where the sand is patched with sea-grass. With the press of a switch, I start to winch in the chain. Link by link, it drops into the locker. The boat nudges ahead, the chain swings vertical and the anchor itself rises out of the water, glinting and dripping like a fish. Our boat throttles forward and we head out of the almost-deserted bay of Luka Soline, into the morning light, moving south across an island-dotted sea.

In the Mediterranean, Croatia is matched only by Greece for the number and beauty of its islands; more than a thousand lie off its shores. Some appear like outsize rocks above the horizon. Some are rocks, grasstufted mounds just clearing the water. Others are so large that their ridges and peaks tangle with those of the mainland itself to produce an ambiguity of land and sea. Exploring the coastline is a riddle that can be solved only by taking to the water – either in the Jadrolinija ferries that serve the islands and the coast like buses or, better still, in a sailing boat such as this 36-foot Beneteau, skippered with panache and humour by Zoran Bradic.

Sea skills come as naturally to the people of these shores as horsemanship does to peoples of the steppe. Zoran spent his school holidays bombing around the coast in his dinghy; in his early twenties it took him only a few years to qualify as a charter skipper. For centuries, the rulers of the Adriatic – first the Venetians, followed by the Austrians – relied on the island communities of Dalmatia (now largely in Croatia) to provide them both with fearless mariners and meticulous shipwrights. ‘This is a sailor’s coast,’ wrote the historian Jan Morris. ‘It grows sailors as other lands grow farmers and miners’.

Out of this port-hopping, footloose milieu stepped the most influential traveller in Western history. Most think of Marco Polo as Venetian, but although he set off from the Italian city for his great Asian odyssey, and lived there later in life, evidence points to his origins in a ship-building family from here, the coast of Dalmatia.

All morning I sit on deck, leaning back against the mast, alternately gazing at the islands ahead and reading from The Travels of Marco Polo. I read of his 20 years in the Far East – the magnificence of the court of the Great Khan with his 12,000 nobles and 5,000 elephants – revelling in the sense of marvels that fills every page. Even by the time of his death in 1324, the book had made Marco Polo famous. Not only did it prove hugely popular in the coming centuries, but – more than any other piece of medieval literature – it fuelled that strange urge in Europeans to jump aboard wooden vessels and sail off into the unknown: to discover, to trade, to conquer.

Looking up from the book, I scan the horizon. Astern is the archipelago of the Paklenis, the islands of Brač and Hvar and the small island of Šolta. In the distance, far to the southeast, lies the tip of Korčula – a few days of meandering and sailing ahead of us. It was there that Marco Polo is said to have been born.

By midday, we approach the shore of Vis. Close up, its slopes reveal stripes of vines, limestone terraces and olive groves. The wind is light and the empty sails flop back and forth, so it is under motor that we round the island’s northern shore and enter the harbour of Komiža.

Nowhere better embodies these islands’ restless, maritime spirit than Komiža. With steep slopes rising on three sides, it is as if the small town – outermost of all Croatia’s harbours – has pulled up a high collar against the land and set its face to the open sea. Dozens of little fishing boats rub fenders inside the quay, men wander around with boxes of tackle and in the Ribarski Musej, the fishing museum housed in Komiža’s fortress, is a display of 130 distinct knots. Every year on the Feast of St Michael, the townspeople propitiate the sea spirits by solemnly burning a boat and scattering its ashes on the water.

Komiža itself could not contain the roving habits of its fishermen, and they migrated all around the world, spreading their expertise as they went. In the 19th century, they set up salting works for pilchards and anchovies on the northwest coast of Spain. Some years later, they reached California and developed one of the world’s largest fish canneries. They have set up enterprises in Alaska, the Galápagos, Samoa and the Magellan Straits. It is said that there are now more Komižans in the Pacific than in their home town.

Off Komiža’s main thoroughfare, Ribarska Ulica (simply ‘fishing street’), I meet Ante Vidovic. He is sitting in the half-darkness of his workshop, tying hooks on a longline. Coming out into the sunlight, he leans against the doorframe and nods down to the water where his boat is moored. Yet fishing for Ante is now only a ‘hobby’. He is retired, while behind him stretches one of Komiža’s sea-tossed lives: for forty years he lived and worked in the far south of Chile.

We stand for a moment, in one of those silences that are so characteristic of men who spend their days at sea, before he volunteers: ‘Do you know that in the Komiža dialect, the language we use for boat parts and fishing is still Venetian?’

Afternoon spreads its honey-coloured light over Komiža. The town settles into evening. No-one is in a hurry. Pottering, sauntering and chatting occupies residents and visitors alike. Drinkers congregate in the shoreside bars. In the coves around the town, family groups lie on the beach while I join the swimmers lolling offshore, our heads bobbing in the gilded waters that stretch out towards the setting sun.

During the night, the wind rises. After days of stillness, everything is suddenly set in motion. I awake in my bunk and listen to the rigging clap against the mast; rain briefly patters on the deck but by morning the skies are clear. Over coffee, Zoran and I chew over the mariner’s eternal question – whether or not to leave harbour. Zoran goes off to the harbour office and reappears with a weather forecast. ‘Twenty to twenty-five knots of wind maximum,’ he smiles. ‘We go.’

We prepare the boat for sea. Around the headland, we are met by a perfect breeze. With sails full and the gunwales dipping, we head south and east, in the direction of Korčula and the ghost of Marco Polo.

The island of Šćedro lies a few miles off our route and that afternoon we nose into the small bay of Mostir, cast anchor, and row ashore. Beside the ruins of a Dominican monastery is a modest beach restaurant run by a man dressed entirely in black, with an impressive pipe curling from his mouth.

This is Stjepan Kordic, whose father was sent to Šćedro as a forest warden. No-one lived on the island then, and now only a few other people inhabit it in the summer, letting rooms and cooking for visiting boats. It's a marginal existence, pursued exclusively by those with a passion for islands. Stjepan is clearly one of these people. He stands in front of his open stove, looking happily out over the bay. The stove’s smoke combines with that from his pipe. He has an old friend staying, a retired sea-captain, who speaks on Stjepan’s behalf.

‘Stjepan carries Šćedro in his heart,’ the captain whispers, with an admiring glance towards him. ‘He carries the island in his chest and in his blood. He cannot live anywhere else. Sometimes he goes to Hvar to see his wife, but after a day he is back on the island.’ We eat fresh tomato salad and grilled codling from Stjepan’s oven, and drink grappa. As we row back to the yacht, Stjepan peels off his black trousers to reveal a pair of black swimming trunks and, boarding an old speed boat, he disappears into the bilges to service the engine.

The wind has freshened. Blowing hard from the north, it sends us bowling down the coast towards Korčula. In the sun, the surface of the sea flashes with white-capped waves. Every now and then, one breaks at our stern, ramping up the boat and surging us forward. This is sailing at its most exhilarating, and Zoran – standing at the helm, generations of Dalmatian seafarers at his shoulder – grins at the thrill of it.

We approach Korčula with the Pelješac peninsula rising above the mast. High up, the vegetation gives way to karst, pale rock dotted with scrub. In centuries past the dogs that patrolled these heights were said to have been bred to produce spotted coats for camouflage, and were thus named ‘Dalmatian’ after the coast.

The walled town of Korčula guards over this strait. For most of the eight centuries from 1000 AD, it was an outpost of Venetian power . The winged lion of St Mark is carved into its main gate, commemorating the great sea battle when the Venetians defeated the Turks at Lepanto. More obvious is the presence of Korčula’s native celebrity. A brief wander takes me past the Marco Polo Mystique restaurant, the Marco Polo bakery and three branches of the Marco Polo shop, selling plaster-cast models of the great man and leather-cased telescopes. Visitors trot by in Marco Polo T-shirts – ‘I have not told half of what I saw for I knew I would not be believed!’ On the sea front the Dubrovnik ferry is docking, dwarfing the town. Its name written on the bows: Marco Polo.

Graveyards are always a good startingplace for local history and, on the wooded slopes above the town, I find Sveti Luka cemetery. To the sound of sparrow song and cicadas, I read the names of countless Korčulans, peer at cameos of proud, communist-era men and headscarved women, before reaching the 19th-century mausoleum of the Depolo family.

The island’s leading authority on Marco Polo is Dr Zivan Filippi. I meet him in the old town, outside the cathedral of Sveti Marko. He is in his sixties, and he speaks with old-world charm and an easily-shared enthusiasm for his town. Korčula’s claim, he explains, rests mainly on the long-term presence of the Depolo/Polo family. ‘Between the 16th and 20th centuries, records show that there were 712 people named either Depolo or Polo born here.’

Earlier papers, he continues, connect the family – at the time of Marco – with the town’s principal occupation of ship-building. As we walk through the shadowy warren of foot-polished alleys, high-sided and narrow, Zivan ignores the town’s trumpeting of its famous son, all the Marco Polo shops and knick-knacks. He speaks of documents and evidence. He points out the Polo family crest carved into a wall. Even in the Marco Polo tower, a belvedere with spectacular views of the sail-spotted channel below, he is more concerned with a few stones in a yard beside it. ‘The tower is many years later than Marco Polo – but here we have discovered the base of a house from his time. It belonged to the Polo family.’

Korčula has one other dramatic link with the great traveller. That evening, we set sail along the island’s eastern coast. The sun is falling, silhouetting the forested skyline and covering our sails in its yellowy glow. Beyond Korčula town is a series of wooded coves where the Polos and others built the ships that helped keep the Venetian empire afloat. We pass the port of Lumbarda before reaching the eastern tip of Korčula, the headland of Rasžnjić.

Here, on the morning of 7 September 1298, the Genoese and Venetian fleets confronted each other in the Battle of Curzola (as Korčula was then known). Commanding one of the Venetian ships was Marco Polo, back from his wanderings. The Venetians were confident of their ships and their mariners, but that day it was the Genoese who were victorious. Marco Polo was taken away in chains, and from a jail in Genoa began to write of his 24 years on the road.

Coming around the headland, I can see the last of Croatia’s islands to the south: the whaleback of Mljet, and Lastovo, almost swamped by the sunset. Beyond them is open sea and a flat horizon. This evening it is harder to imagine the horror of a 13thcentury sea battle, the timber-clash and slaughter, than the young Marco, 27 years earlier, filled with the fear and curiosity that begins all great journeys, sailing off between these islands for the Far East.

The article 'Sailing in Croatia' was published in partnership with Lonely Planet Magazine.