Ask anyone who has spent long enough on the Cornish coast and they will tell you that the sea has a voice. It is there in the tide race off the headland, in the suck of water over a sandbar, in the wind that finds its way into the chimney of a fisherman's cottage. Cornish mermaid stories grew out of that voice. They are not simply pretty tales of girls with tails. They are warnings, tied to particular coves and particular tides.

Helpers and Tempters

In the old tellings, a mermaid can be either. She may swim alongside a boat in foul weather and warn the crew to make for harbour, or leave a comb on the rocks as a sign of luck for a family that has treated the sea kindly. She can also sing a man away from his home, his boat and his senses, and he is never seen on land again.

That double nature is the point. The sea gives, and the sea takes, and it does not much care which. A story that makes the mermaid only kind, or only cruel, has lost its teeth. The good versions keep both possibilities open right to the end.

The Mermaid of Zennor

The best-known Cornish mermaid belongs to Zennor, between St Ives and the wild north coast. In the church of St Senara there is a carved bench end showing a mermaid holding a comb and a mirror. The tale says a woman with a beautiful voice came to the church, Sunday after Sunday, and listened to the singing of a young man named Matthew Trewhella. He followed her down to the cove, and neither of them was seen again. Some tellers say his voice could still be heard singing out beyond the headland.

Notice how much of the story is anchored in real things: a bench end you can go and see, a church, a cove with a name. The warning is about vanity as much as about the sea. Matthew was admired for his voice, and it was praise of that voice that drew him off the safe path. The tale does not say he was drowned. It says he went willingly, which is worse.

The Doom Bar and the Price of Greed

At Padstow, the great sandbar across the mouth of the Camel is called the Doom Bar, and it has wrecked a great many ships. One legend says a mermaid was shot at by a man on the shore. Before she left, she cursed the harbour, and the bar grew where nothing had grown before. Other versions put the blame on a sailor who tried to take her comb, or on a fisherman who broke a promise made to her.

Whatever the telling, the moral is consistent: do not take from the sea what has not been offered, and do not harm what you do not understand. It is also, quite literally, a hazard warning. The bar is real, it shifts, and boats still come to grief on it. A good coastal story often does two jobs at once.

What the Tales Are Really Warning About

• Vanity. Being flattered is dangerous on a coast where the weather can turn while you are admiring yourself in a rock pool.
• Greed. Taking more fish, more wreck, more treasure than you need invites a reckoning. The old drolls give wreckers and pilferers short shrift.
• Ignoring the tide. The mermaid's invitation always seems to come with time to spare. It never does. Estuaries and causeways flood from behind you, cutting off the route home.
• Ignoring local knowledge. The stranger who laughs at the old stories is usually the one the story is about.

Reading the Coast, Not Just the Story

Cornwall's tides are among the largest in Britain, and they move faster than most visitors expect. Before you walk a beach, a causeway or an estuary path, check a tide table for the exact place, not the nearest big town. Ask at a harbour office, a café or a bait shop what the water does there. Local people will tell you about the Gannel, the Camel, the rip currents on the north coast beaches, the standing waves at the mouth of a cove.

Take the sea seriously and you will enjoy it more. Keep an eye on your escape route. Never turn your back on the swell. Keep children within arm's reach near the water. If a wave looks wrong, it is wrong. The old mermaid tales are simply this advice dressed in feathers and scales.

Keeping the Tales Alive

Cornwall has a strong tradition of spoken storytelling, and the old collections are still wonderful to read aloud. Look for the nineteenth-century gatherers such as Robert Hunt and William Bottrell, who wrote down tales from fishermen, miners and farmers before they were lost.

If you want to tell these stories yourself, keep them short and keep them local. Name the cove. Mention the tide. Tell them at the place they belong to, if you can, or by a fire when the wind is up. Let the gruesome bits stay gruesome, and do not tidy away the ending. Then pass them on, the way they have always been passed on along this coast.