Medicines have been discoverd too Sinking of RMS Republic Selection of bottles on seafloor Robobit arm collects bottles in a bucket

There are many wrecks all over the world where an inquisitive diver may find a cache of bottles, but in some cases the potential haul has been so great that the site has been the subject of a painstaking salvage operation. Such was the case with the Jönköping, a 20m, two-masted schooner, built in Sweden, which sank off the coast of Finland in 1916 after being torpedoed by a German U-boat. When she went down, she was carrying 100 tonnes of cargo, among which were 4,400 bottles of 1907 Heidsieck & Co Monopole champagne and several barrels of Cognac.

When stories of the Jönköping shipwreck and its champagne cargo began to roll off the presses, the details were hazy at first. Reports had the number of bottles ranging from under 1,000 to well over 5,000, with a value of between a few pounds per bottle and US$15 million for the entire haul.

As more became known about the ship and its cargo, the question of the wine's value remained. On the one hand, oenophiles were quick to point out that the conditions on the sea bed provided the perfect environment for ageing wine. At a depth of 64m, the wine had been kept at an almost constant temperature of 4ºC, away from the harmful effects of ultra-violet light. On the other hand, it was all too plausible to believe that over the course of 81 years on the ocean floor, sea water had penetrated the corks, transforming it from an estimated $3,000 vintage into a $20 curiosity.

Liquid assets The wreck of the Jönköping was finally discovered in 1997 by Claes Bergvall and Peter Lindberg, who went on to form the salvage company 'C-Star', and acquire the rights to the cargo. Trimix divers assessed the state of the wreck and found out it was a prime candidate for raising via a crane.

They overcame visibility of less than 20cm to place the cables and successfully raise the wreck in a painstakingly delicate operation. The company abandoned the original plan to turn the wreck into a museum ship and dropped it back to the ocean floor, but not before salvaging 2,000 bottles of fine vintage champagne.

But could you drink it? Initial tests were promising, with Laurent Davaine, the Director General of Heidsieck and Co, claiming, 'After more than 81 years spent in the wreck of the Jönköping, this wine still shows an amazing balance. It has not been denatured and has kept a beautiful structure.'

Later that year, single bottles of the 1907 were selling for £2,000, breaking the world record for the highest bid ever for a single bottle of champagne and putting salvaged wine firmly on the map for treasure hunters.

Under pressure The Jönköping may have been the most successful salvage of wine to date, but it was by no means the first. Ten years earlier commercial divers exploring the wreck of the RMS Republic off the coast of Nantucket on the eastern US coast accidentally found themselves in the wine locker (at a depth of 86m), surrounded by some of the most famous vintages of all time. With salvage costs running at $10,000 per day, the divers were aiming for the Republic's fabled 'Billion Dollar' bullion room, but when they ended up in the wine locker, supervisors took the decision to salvage the wines instead.

With no hope of raising the liner to the surface, the onus was on the divers to retrieve the bottles as they continued their search for the Republic's gold. In a round-the-clock salvage operation, they worked ten-hour shifts in hot-water suits, breathing Heliox and working out of a diving bell chamber. Helmet-mounted video cameras sent live feeds back to their support ship, The Inspector, where supervisors monitored every move. By the time they had finished, 300 wine bottles had been recovered.

'While the wines could have [had] considerable value, we were unprepared for their recovery,' said salvor Martin Bayerle. 'On exposure to air and the significantly reduced pressure at the surface, the corks dried, lost cohesion and some were expelled due to the original compression of the cork into the bottle - and the contents of the bottles that we had recovered were lost. The champagnes were the few exceptions, because of the shape of the cork. Exterior pressure only made the seal tighter, but once the corks dried, and with the sealing metal wire weakened or completely gone, the corks at the surface soon popped.

'We did drink two bottles of 1898 Möet, rather than see them go to waste. Next time, we'll be prepared to recover the wines. For non-effervescent wines, we would insert a syringe into the corks so that the internal pressure would not force out the cork when retrieved and exposed to the reduced surface pressure. Champagne corks would be secured underwater. On surfacing, all wines would be identified, corks removed, contents sampled for salt-water intrusion, re-corked - all in a pressurized atmosphere - and then re-labelled.'

By coincidence, one of the other great bottle wrecks was that of the SS Republic, a sidewheel steamer lost during a hurricane in 1865. In 2003, it was found by the professional salvage operation Odyssey Marine Exploration at a depth of 525m, 100 miles off the coast of Georgia, USA. More than 50,000 coins have thus far been recovered from the ship, in addition to 200 different types of bottles - a rich snapshot of 19th-century Americana.

This incredible collection, from a time when practically everything was bottled, is the subject of a new book, Bottles from the Deep ($12 plus p&p from www.shipwreckstore.com) by Ellen G Girth, in which the reader gets a tour of bottles originally made to contain anything from bear-grease hair pomades to hot sauces, beer and wine.

Nature's wine cellar Apart from the pressure, the bottom of the ocean provides the perfect environment for ageing wine. Common consensus among wine buffs is that wine should be stored between 4.5 and 15.5ºC (40 and 60ºF), in total darkness. With the sea offering conditions very close to this, some wine producers have actually taken to what has come to be known as 'underwater cellaring'.

Vina Casanueva, a Chilean wine producer, has been practicing underwater cellaring for some time now and the company's general manager, Patricio Casanueva, explains, 'These wines spend at least six months underwater, with a constant temperature of 8ºC [about 46ºF]. Also, very important is the sunlight refraction that crosses the sea and reaches the bottles. And, of course, the water currents.'

Bottles deliberately stored this way can have special corks fitted, but bottles lost to the deep by accident had no such benefits. Vernon Singleton, Professor Emeritus at the department of Viticulture and Enology at the University of California, examined several bottles recovered from a First World War wreck and assessed the quality of their contents. 'I received four bottles recovered carefully from a sunken vessel in Agana Harbour, Guam. Two turned out to be brandy and were contaminated by salt water. Two others were wine and were not so contaminated. There were no labels and the bottles were scratched by rubbing caused by wave action.

'The sparkling wine bottle was almost half empty, I believe because the inside pressure had forced some of the liquid out, but had not let seawater in. The wine no longer retained CO2 gassiness. It resembled a weak white table wine with a watery (but not salty) character. The sweet vermouth had been red and had considerable deposit. It, too, tasted weak and watery, but not salty.

'There were no special desirable flavours as can occur with normal cellar ageing. The corks still seemed in good condition, I assume the brandies had had wooden caps that had come off. The remainder was short and that is probably why the salt got in. The diver said that he had brought the bottles up by holding his thumb on the stoppers and making sure they were not loosened.'

A cautionary tale In 2004, divers from the Folkestone Diving Club in Kent discovered 20,000 half bottles of a 50-year-old commemorative Cuvée after their echo-sounder detected an unnamed wreck and the divers discovered the cargo. Again, the champagne stood up to the scrutiny of professional wine experts… the club has remained secretive about the wreck's location. Divers returning to the surface with even a single bottle should take care not to pop the cork and down it in a celebratory return to the surface, as they could be wasting thousands of pounds. Even beer can have sky-high value. Take the case of the divers who opened and drank one of eight bottles of beer they recovered from the Loch Shiel off the Welsh coast.

Jim Phillips, one of the divers, told reporters: 'It was flat but it had not been contaminated by the salt water even after all those years on the sea bed. We later had the find valued at £1,000 a bottle, so that was certainly the most expensive pint I have had.'