Strange things happen the deeper down you go beneath the sea. Being underwater is the closest many of us will get to the Twilight Zone, when things are never quite what they seem. For every fish that looks like a fish, there's another that's a monster, lurking behind a lump of coral waiting to tear your head off. On the ocean floor, for instance, what looks like an outcrop of rock festooned with blobs of green algae is in fact a family of stone fish. Stand on one and it will kill you. Then there are the circling sharks. Which sounds like the greatest cliche in maritime reportage but circling is what sharks do, usually in gangs.
You can see both at Nausicaa, an innovative sea museum situated, appropriately enough, on the coast of France at Boulogne. And the sharks, especially, are every bit as terrifying as legend has them.
But there are more than two fish in the sea and Nausicaa has its work cut out trying to represent the contents of all the oceans of the world, from the tropical lagoons of the caribbean to the bottom of the North Sea. Futuristically designed, Nausicaa tries to mirror the experience of being underwater as closely as possible. It is dark and eery with a background of electronic music which has been skilfully blended with whale song.
There is a refreshingly non-conformist approach to presentation. An outsize transparent tube, which reaches from floor to ceiling, encases hundreds of gently pulsating jelly fish, engaged in an endless ballet on unseen currents of water. A giant inverted pyramid, suspended from the ceiling, is teeming with tuna. More than 1,000 multi-coloured tropical fish swim in and out of a thriving coral garden, where the heat and humidity of their environment is carefully controlled by an air lock. Some tanks have been constructed with observation bubbles which means visitors can get closer to the ocean bed and its peculiar inhabitants than Jacques Cousteau ever dreamed of. It is captivating and magical but there is more to it than mere spectacle. Nausicaa's principal aim is to educate its visitors about the fragility of a vital ecosystem and how the sea's precious resources should be carefully husbanded for the future. So the tuna pyramid is cheek-by-jowl with a life-size trawler, complete with sound effects of shrieking winches, howling winds and roaring engines. This forms part of an examination of the fishing industry and how many interests have to be taken into account in deciding fishing policy.
There are interactive panels and quizzes and when you are not being lulled into a deeply meditative state by all the neon lighting and whale song, there are sobering facts to jolt you back to reality. Did you know, for instance, that 2 billion cubic metres of untreated sewage are emptied into the North Sea each year, along with 10,000 tons of mercury, 14,000 tons of lead and 45,000 tons of zinc? How the Mediterranean, which is largely enclosed, ever manages to look as blue as it does is one of nature's puzzling conundrums.
Nausicaa is a cross-curricular paradise, and one that is particularly attuned to the needs of school groups. There is a multi-media library of books and videos, linked exhibitions, a cinema showing sea-related documentaries and a separate teaching room. It also organises young people's activities throughout the year, from beach clean-ups to science days and learn-too-dive weeks. To see as much of the undersea world in the raw, you would need to learn to scuba dive which is both very expensive and dangerous. And there is no reassuring wall of perspex between you and the moray eels from hell.
For more details contact Nausicaa, Centre National de la Mer, Boulevard Sainte-Beuve, 62200 Boulogne-sur-Mer, France. Tel: (010 33) 21 30 9898. Or contact the French Government Tourist Office at 178 Piccadilly, London W1V 0AL. Tel: 0891 244 123. Group rates are available as are free preliminary visits for teachers. A visit to Nausicaa can be combined with one to the historic town of Boulogne with its medieval castle and museum