There is a true story of the ocean, written in a book of family memoirs by Robert Louis Stevenson. It concerns a ship about to founder in an overwhelming sea; the stricken vessel is close to an island hamlet in the north of Scotland, and the unfortunate captain sends out a signal of distress. At that moment the doors and windows of the little village are opened, and the inhabitants come out. But they do not rush to their boats, or offer any assistance at all. They stand, with folded arms, and watch the destruction of the vessel; they wait silently for the ship to sink, since then their work can begin. Once the crew and passengers are drowned, they can sail out and claim the cargo as their own. They are known as “wreckers”, and this exciting book represents their history.

“Wreckers”, as their name suggests, are those who earn their living by scavenging from sunken vessels. They have been known to put out false lights, to imitate the sound of fog-horns, and even to construct crude “stage sets” of harbours and cottages to lure unsuspecting voyagers on to the local rocks. They have been known to sabotage lighthouses in their greed for the spoils of the sea.

There are wreckers still all over the world; wherever there are ships and sea, there will be some who are interested in their collision. Bella Bathurst has wisely decided to concentrate on the coastline of the British Isles, however, where a combination of difficult seas and hazardous coasts provides a unique opportunity for those who make a living out of maritime distress. This is in any case a sea-girt kingdom; it has always been defined by the sea, and the sea is part of its destiny. It is not surprising that wreckers are as English as muffins and cream teas.

It might of course be considered an old-fashioned profession, associated with 18th-century piracy or with 19th-century profiteering. In the public mind it should surely be associated with four-masted schooners or ancient frigates. But Bathurst makes it clear that wrecking is as big a business as ever. In the days of global positioning systems, the sea is as dangerous a place as in any other century.

The sea is primeval. It is the most ancient place on earth. It has remained unchanged, in every respect, for 3,500 million years. The oceans were formed in the depths of pre-Cambrian time, and there is not one drop more or less than at that inconceivable beginning. It is not, in other words, user-friendly. It is a fearful thing. The fact that it is alien may give some justification to the wreckers’ belief that “a man rescued from the sea will prove the bane of his deliverer” . He who saves a drowning man will receive some wrong or injury at his hands. As one native of the sea put it to Bathurst: “You’ve deprived the sea of its prey. And the sea will take you, or one of your family, in place of the person you’ve saved, because you’ve cheated it.”

This is, perhaps, the reason for the tradition among fishermen of meeting a death by drowning with fatalism, if not with equanimity. If a man fell overboard he made no effort to save himself. More likely than not, he had never learnt to swim. The sea was the great destroyer. It had claimed him at last.

The sea is so ancient that it also seems to dissolve all claims to ownership. Any human association is tangential and temporary. Wreckers have always believed that they have an “absolute right” to anything taken from an abandoned ship. It is known as “the sea’s bounty”, which is a matter of custom rather than of law. There is, of course, another, and perhaps more rational, explanation. The goods in question would remain unsalvaged, and unclaimed, if the wreckers did not take them as their own. The ocean is also of uncertain jurisdiction. Who owns the sea? The sea has always been treacherous. Fishing and seafaring are by a long way the most dangerous occupations; that is why mariners had once to be press-ganged rather than volunteering their service. Only the brave, the foolhardy or the desperate would once have contemplated a career aboard ship.

That is perhaps why Bathurst opens her narrative with a disquisition on the dangers of being set adrift, emphasising the fact that this book is as much about the cruel sea as the cruel salvagers. A human being can survive for 40 to 60 days with water and no food, but for only a week without water. The sea will also kill you more quickly in other circumstances. It freezes you to death.

In the past, men and women went to their deaths unknown and unrecorded. The official total of known wrecks around the coastline of Britain is about 33,000, but there must have been many thousands more which were not registered. The worst county for wrecks is also among the smallest: Durham has 43.8 wrecks per mile of coastline. The sea there is heaving with memories of death and disaster.

Nothing is as perilous, however, as the Goodwin Sands, otherwise known as “the ship swallower”. A large vessel can disappear within its depths in less than an hour. Great ships have been dragged down, only to settle on the chalk bed that lies beneath the voracious sand. In this cloistered environment they are still preserved. It was only to be expected that the local inhabitants would take advantage of what was a giant quagmire. Bathurst tells the stories of the Deal wreckers or “levellers” who were closest to the sands. They would come to the assistance of ships in distress while at the same time picking up whatever merchandise came to hand. The quicker and greater the distress, the better.

There are even more assiduous wreck- chasers. On the island of Stroma in the Orkneys, now deserted, much of the inhabitants’ income came from what Bathurst describes as “piloting, smuggling, illegal whisky distilling and wrecking”. It was deemed impossible to beat the pirates of Stroma in their pursuit of sinking trade. On one occasion, when a ship named Pennsylvania foundered, the islanders picked up a grand piano, two Cadillacs, typewriters, hogsheads of American tobacco and a hundred other various items. They were lucky with their territory. Here the North Sea and the Atlantic clash in a tumult and frenzy not seen on any other part of the British coastline. Between 1830 and 1990 more than three vessels a year were wrecked in these waters.

When the Cita was wrecked on the Isles of Scilly, Bathurst compared the event with “having Selfridges crash land in your back garden — a Selfridges with all the prices removed”. For many years the islanders walked round in Ben Sherman shirts and Ascot trainers. One local divine described them as “the sons and daughters of God’s providence”, which is one way of looking at it.

Bathurst’s descriptions of these horrors or adventures — according to taste — are precise and graphic, but also poignant. It is as if she were half in love with the cruel sea. She documents its shifts and moods; she celebrates its passions and its rages; she mourns its vengefulness and rapacity. She understands that the beautiful can also be the sinister.

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