They are armed to the teeth, ruthless and desperate, but claim to adhere to their own code of conduct. They have grown so powerful that they threaten to cut a vital trade route, and fearful merchants are crying out for naval escorts. In the seas off Somalia, it seems as if the so-called heyday of piracy at the turn of the 18th century has returned, with an estimated 1,000 pirates organised into five main fleets stalking a latter-day Barbary Coast.
High-speed plastic skiffs, AK-47s and rocket-propelled grenades have replaced the galleons, flintlocks and cannons of old, and their targets are no longer ships full of Spanish gold, but oil tankers and human hostages to be ransomed for millions of American dollars.
However, the deadly intent is the same and the threat to shipping is becoming as serious, with merchant marine organisations warning vessels may be forced to stop using the Suez Canal and make the long detour round the Cape of Good Hope. It seems almost unthinkable, but a route taken by tankers carrying a third of the world's oil could be closed because of piracy, a crime many in Britain will associate only with semi-legendary tales of Blackbeard and Johnny Depp's comic turn as Captain Jack Sparrow in the film Pirates of the Caribbean.
In recent years once-notorious areas, such as the Malacca Straits between Indonesia and Malaysia, have been relatively quiet. But a surge in attacks on shipping in the Gulf of Aden and off the Somalian coast, coupled with a dramatic rise in the ransoms, has led to fears that newly adopted, lucrative tactics will be copied elsewhere. Somalian pirates have invested in "mother ships" to carry the small speedboats used in their attacks further out to sea, extending the danger zone from 50 to 200 nautical miles off the coast. And they are seemingly unafraid to take on the most formidable of targets, as shown by the continuing stand-off between the captors of a Ukrainian ship, carrying Russian tanks, and six US warships.
With a frigate on the way from Russia and clearance from the Somalian government to attack, the pirates might be expected to flee. Instead, they are calmly demanding nothing less than their stated ransom of $20m (£11m) and promising to fight if attacked. Excluding this sum, Somalian pirates are expected to take $50m this year.
In 2004, there were just five attacks and attempts on ships in the seas off Somalia, but so far this year there have been more than 60, accounting for nearly a third of the 198 incidents globally. Insurance premiums for cargo ships passing through the area have gone from $900 to $9,000 in a year.
Asked if the world was seeing the beginnings of a new age of piracy, Giles Noakes, chief maritime security officer at Bimco – the largest of the international shipping associations – says: "That's not a question I'd like to answer. It's not a question I like to hear. People start thinking about Pirates of the Caribbean and all that rubbish. This is 21st-century criminal activity using violent means."
Mr Noakes rates the threat to Suez as very serious, warning that shipping companies are considering avoiding the area, and says such dangers could spread elsewhere in the world.
"It would be naive to think this isn't being watched by other people carrying out acts of piracy at the moment. It is not an isolated thing," he says. "The armed robberies in the coastal waters of Nigeria are getting almost as extreme. The violence being displayed is as extreme and the number of attacks is almost as numerous, but it is little publicised."
He is shocked that the problem has not previously drawn more international attention, as 14 ships and more than 300 sailors are currently being held to ransom worldwide.
Some in the industry resort to what Mr Noakes describes as "unfair and unreasonable navy-bashing", but he says the lack of an effective deterrent stems from a lack of political will. "That's the fault of governments whose strategic, commercial interests are being threatened. I don't think they have sat up and smelt the coffee on that yet," he says.
The payment of ransoms is a delicate issue, but Mr Noakes says that in reality companies often have little option if they want to save the lives of the crew. "We never think a ransom should be paid, but we have no choice other than to advise our owners to do that," he says. "A lot of them are trying to negotiate the price down, and a lot of them do so quite successfully."
Despite these efforts, there has been rapid inflation in the price of ransom and this, according to Roger Middleton, a Chatham House researcher specialising in the Horn of Africa, is one of the main reasons for the rising number of attacks.
"A few years ago they might have been as little as $10,000," he says. " We are now seeing these ransom payments regularly topping $1m." A more organised approach is being taken, with the use of mother ships, GPS devices and even the adoption of an employees' code of conduct.
"It is a serious business going on here. People are making a lot of money and they are investing in equipment, in boats, in men and in weapons," says Mr Middleton. "They live in the poorest part of the poorest country in Africa and it is easy to understand why they would resort to crime, but that makes them no less scary for people who are captured and threatened."
Captain Colin Darch, 71, of Westward Ho!, Devon, knows this all too well. Earlier this year, he was 70 miles off Somalia in a tugboat en route from St Petersburg to Singapore when armed pirates attacked. Shouting and firing into the air, the pirates came on board and so began 47 days of captivity for Captain Darch, his Irish chief engineer, Fred Parle, and Russian crew of four. They tried to escape but were forced to give themselves up.
Captain Darch recalls: "I really was a bit worried they [the pirates] might punish us for giving them so much trouble. The young guns were shouting abuse at us and shooting their guns. Then Omar, their leader, appeared. He grinned and held out his hand. It was like we'd just had a good game of squash and I'd lost."
They were freed after the ransom was paid and the pirates transferred to another boat. He says they were generally well treated. Other Somalian pirates have spoken of a written manual, laying down rules on the treatment of hostages, including a ban on sexually abusing female hostages and shouting loudly at captives, as well as requirements to provide food and drink and allow their prisoners to sleep and use the toilet.
But Giles Noakes says no one should believe this is a sign the pirates have a genuine concern for their hostages. "These guys who say they have a 'pirates' code' – it's a bit of a euphemism for saying: 'We are acutely aware the money is in the hostages, not the ship.' They are not stupid."
Pirates by numbers
£9bn estimated annual losses due to piracy worldwide.
90-95 percentage of world trade carried by ship.
300 approximate number of sailors currently held hostage by pirates worldwide.
198 the number of pirate attacks so far this year.
$1m average ransom for a ship taken by pirates.
1,000 estimated number of pirates in Somalia.