Something’s wrong…

Then the plane jerks, the engine roars, and you can see the pilot fighting to bring it under control. He twists the rudder and opens the throttle, zooming overhead, narrowly missing a yacht docked in the bay.

You smile slowly.

Inside the cockpit, it must feel like the plane’s become inexplicably heavier – and you can see the pilot glancing around, trying to see whether he’s forgotten to unload the ballast or unmoor a line. But it’s dark, the waves pitch-black beneath him, and he has no way of seeing what’s only too obvious from the ground.

Hanging below the seaplane, knotted tightly to its skids with rope stolen from the lifebelt stations, are three spherical, dangling buoys, swaying wildly in the wind. They’re not particularly heavy, designed to float easily on the water – but they’re not what the pilot needs to be worried about.

Each mooring buoy in the harbour is attached to a long, iron chain, which in turn is bolted to a six-ton concrete anchor block, wedged in the sea floor. Boats hook up to these buoys to stop themselves drifting away overnight. It’s an ancient design, but one that anchors them permanently to the seabed until the line’s removed. Even a ten-ton trawler can’t get away once it’s hooked up to one of these; you remember being impressed when your tour guide pointed that out.

The tiny, lightweight Cessna 208 seaplane, made of hollow steel and polished wood, doesn’t stand a chance.

You watch as the plane circles, climbing higher and higher, throttle opening up as the pilot recovers confidence. The buoys dangle from each skids, looking like carnival decorations, still invisible from above.

But the rope is rapidly running out.