If the bearing is correct, the wreck of the windjammer should be exactly below us. We are making a documentary for Swiss-Television DRS, and planning to spend several days diving the "mystery wreck" of Bonaire.
     Our first task is to attach a buoyline. The wreck lies exactly on the southern border of the Caribbean island's national park, so official approval is required. That had proved no problem, so long as we met one condition: we had to sink the buoy immediately after diving, to prevent others diving the wreck or allowing its position to become too obvious.
     My buddy is Dominique Serafini, who worked for 18 years on the vessel Calypso, bringing the adventures of Jacques Cousteau and his team to life on paper through his gifts as an artist and designer. His work can be seen in more than 200 children's books published worldwide.
     Dominique spends the winter months on his catamaran in Bonaire, and has already done many dives on the windjammer and produced a colourful painting of it.
     To work efficiently, remain within our time limit at depth and keep a clear head below 50m, we are to breathe heliair from twin 12 litre tanks and decompress with nitrox and 100% oxygen.
     While carrying out final checks on my equipment, a mixture of expectation and nervousness grips me, as it always does before such first-time descents to wrecks. Today it is especially intense, because I am aware of my luck in getting the chance to explore a totally preserved three-master. And my sense of tranquillity returns as soon as I jump into the water.

Bonaire Divers found the Mairi Bhan in 1981. Before then it had been known only as "the windjammer". Mairi Bhan is Gaelic for "Bonny Mary", and more is known about it now.
     Commissioned in 1874 by Englishman Paul MacIntyre, the 1315 ton iron clipper was built in Glasgow by well-known shipbuilder Barclay, Curle and Co, to carry hand-crafted goods from New Delhi to London for a thriving import business.
     Contemporary accounts called the Mairi Bhan one of the "handsomest" ships of the Pacific. Her maiden run from Glasgow to Port Chalmers, New Zealand, was completed in about 75 days, outstandingly fast for the times. She plied her Pacific route until near the turn of the century, when she was sold to the Italian firm of Denegri & Mortola, based in Genoa.
     The Italians turned the Mairi Bhan into a tramp that would put into any port where cargo could be found. In 1912 she carried leather goods, fabrics, olive oil and marble from Italy to Trinidad. She traded this cargo for a load of asphalt, charted a course for Marseilles and rode the tradewinds along the coast of Venezuela.
     She was starting to make her north-east turn to cross the Caribbean when she was caught by a sudden squall boiling out of the Venezuelan coastal mountains. Captain Luigi Razeto, the ship's master since 1907, decided to make for the protected roads off the island of Bonaire, but got blown past it to the north.
     He tried to double back down the coast, but huge seas crashed into the ship. She ground onto the reef and started to list. The anchor was let go but wouldn't catch on the crumbling coral surface.
     Barrels of asphalt started to shift in the holds below, many breaking open. The fumes built up and were apparently ignited by a kerosene lamp.

There was a sudden explosion and a raging fire. Four crewmen perished before the remaining 28 managed to abandon ship and reach the shore, only metres away. The majestic clipper continued to heel to starboard, with water crashing over the deck and into the holds.
     The Mairi Bhan slipped below the sea, her centre mast snapping off as it snagged the shallow reef. The rest of the ship slid over it and down the drop-off, dragging the broken rigging and anchor along.
     The ship ended its death-slide at the bottom of the drop-off, on its port side with its keel facing the shore and its remaining masts pointing away from the reef, down the sloping bottom. The starboard rail is at 43m.
     The molten asphalt spilled out of the holds like lava, hardening on the bottom to form a flat black layer. The Mairi Bhan settled down to wait for the next humans to come across it.

The visibility is great when I get down there, with almost no current. That is rare up here on the north-west cape of Bonaire.
     Within a few metres I know we are in the right place. At first blurred, but increasingly unmistakeable, the outline of the wreck peels itself away from the diffuse blueness.
     We land on the stern, which displays the typical overhang of all sailing ships of this vintage.
     It takes us a few minutes to fix the chained extension of the rope and send the other end to the surface with a lifting bag. We still have plenty of time and gas left to explore the wreck and get a good impression of it for our storyboard.
     As the wreck lies on its side on the sloping bottom, the deck drops like a steep wall into the depths. The free-fall is fantastic, because the wreck, which is covered with coral and sponges, seems to become increasingly big as we descend and our perspective changes.
     On the seabed, at 55m, some strange formations attract my attention. They are made up of the ship's cargo - tons of asphalt. Like solidified lava, the whole of the port side has coalesced with the seabed.
     The deck-planks are all rotten or burnt. The inner part of the wreck is a skeleton of iron constructions and stairways - perfect scenery for spectacular pictures. As above on the hull, nature has taken control of everything.
     To obtain a complete overview of the ship, we swim along the main mast out to the open water.
     At the enchantingly overgrown top, far more than 60m deep, we have a fantastic view. We can see as far as the stern and the torso to the tip, with its protruding bowsprit. To be able to digest such impressions without becoming euphoric, we would need at least 15% more helium in our tanks!

It is sad to leave this place, but we have to make our way back up to the starboard side. Very slowly, hand over hand, we ascend the buoy line.
     Our decompression time will be lengthy - long enough to absorb our impressions and create plans for further descents to Bonaire's "mystery" wreck.

The sailing ship is partially overgrown with corals and sponges


Over the bow at 55m


Kurt Amsler picks out features of the wreck in a painting of it by Cousteau team-diver Dominique Serafini


inside the wreck


An overgrown bollard on the deck


the keel from the stern end


another view of the stern