Aquarium offers a fish-eye view of sea: Transparent tunnel is star feature of pounds 4m venture aiming for 250,000 visitors a year

IN A disused quarry underneath the Forth rail bridge, the finishing touches are being put to Britain's first 'walk-in' aquarium.

Visitors will view fish from a see- through acrylic tunnel at the bottom of a 1 million-gallon tank in what is said to be the first aquarium of its kind in the northern hemisphere. A total of pounds 4m has been spent to realise the dream of Alistair Davidson, an Edinburgh architect.

Deep-Sea World at North Queensferry is the latest addition to a chain of aquariums begun in New Zealand in 1975, where acrylic glass technology allowed visitors to become part of the undersea world.

After success in Australia, Under-Sea World opened in 1991 in Singapore. In its first year it attracted more than a million visitors. In Scotland, only Edinburgh Castle achieves that level of tourist success. For Deep-Sea World to be judged a financial success by its backers it will need 250,000 visitors a year, the same as Stirling Castle.

Deep-Sea world will eventually hold 5,000 fish of 100 species, providing an underwater safari that will inform visitors about Scotland's marine environment.

Already shoals of native fish have made their home in the million gallon tank; crustaceans, rays and a three-metre porbeagle shark will soon arrive. The concept of curved underwater viewing tunnels was developed in Auckland by Ian Mellsop, a civil engineer. The 112m (122yd) tunnel at North Queensferry will be the longest ever constructed for an aquarium.

The project will be seen as a partial response to recent criticisms from naturalists who believe Britain's leading world role in maritime research is not mirrored by aquarium facilities of the standard of those in New Orleans, Tokyo and Boston.

Deep-Sea World is a tourist venture, with three-quarters of its cost raised from the private sector. However, its status as an enclosed marine eco-system and as an example of how technology can help move the idea of captivity further away from mere circus side-shows should ensure interest from oceanographers and marine biologists.

Phillip Crane, chairman and chief executive of Deep-Sea World, said: 'We have a commitment to raise awareness of the marine environment through entertainment and education and in so doing create a centre of excellence.'

(Photograph omitted)