To Hull and back - sharks allowing

We were 30ft underwater, admiring a golden trevally fish and a southern sting ray, when some of the world's most in-your-face dentures stole up out of nowhere.

'Duck!' shouted someone, instinctively but too late, as the 6ft sand tiger shark skimmed our heads. If there hadn't been 6in of acrylic between us and it, we would have been, well, wet (these sharks are already well-fed).

For one of the best views of the ocean from inside, head for Hull and walk the underwater tunnel beneath Europe's largest fish tank within The Deep, the £45million tourist attraction which opens on Saturday.

The seafaring city is famous for landing cargoes from distant shores.

But the vision for The Deep came from closer by, on a train journey from London in 1995 where council representatives Colin Brown and David Gemmell hatched a plan based around something Hull did rather well - fish.

There are already more than 20 aquaria in the UK. So this would have to be deeper, bigger, better. Something that didn't even have a name, so they gave it one - submarium.

Once the cash - including £21million from the Millennium Commission - was sorted out, the grand design took shape. Architect Sir Terry Farrell, who did the M16 block featured in the latest Bond movie, created a building in the shape of a capital A on its side, clad in aluminium and black enamelled tiles, dead centre on the Hull waterfront and jutting out into the river Humber.

And that's where I found myself, four floors up, venturing out onto the point of the A for the best view in town. I felt like Leonardo di Caprio on the prow of the Titanic, but without Kate Winslet.

'We are one of the three biggest things on the river,' said Colin, gesturing to the other two - the Humber bridge and the Pride of Hull, one of the world's largest ferries.

The Deep's ambition is to tell the story of the oceans 'in time, depth and latitude'. So best not to arrive just before closing time.

After a quotation from Genesis, the first thing you see is a computer generation of the Big Bang. Then a long sloping walkway under a wall of 3D fossilised sea monsters takes you past vast aeons of time.

A series of presentations on the latest plasma screens takes up the tale. One screen tempts you to design your own creature and see it swim in a virtual ocean. Mine, a concoction of misshaped fins and awkward flippers, lost its first battle and became extinct.

Then we hit the serious water. The glass-sided Coral Reef tank serves up flying gurnard and bonnet head, a bonsai version of the hammerhead shark.

The best is saved for last. The 10 metre deep, 2.5million litre Endless Oceans tank contains seven species of shark and as many fish of many colours as you could expect to see anywhere, indoors.

A series of small side tanks focus on a species or theme. In the camouflage tank one angular customer does a good imitation of a lemon that has swallowed a box.

Time will tell if the Deep becomes the international attraction Hull hopes it will be but the council is quietly confident. A million people a year pass through for the ferry to Europe.

I finished my tour in the city itself. Fortune hunters, disappointed with the lack of gold underfoot in the streets of London, should try Hull instead. It is literally paved with fish. You don't go far in the old city without treading on an oar fish or a John Dory carved in York stone, cut in steel or set in polished slate. Hull actually tells pavement jokes - a dogfish chasing a catfish, a shark outside a bank. Spot all 41 and you get a certificate.

Not so long ago Hull was full of mean back streets where you never went for fear of being tugged down an alley and forced to work as ship's crew. Now most old port buildings and merchants' quarters are smart architects' offices and wine bars. My guide led me from Princes Quay, a three-storey shopping centre on stilts over an old dock, to the UK's largest parish church - Holy Trinity - to Ye Old White Harte. No need to distress this ancient pub's old wood: nothing much has changed since upstairs they plotted the closing of Hull to King Charles.

This year the four (free) city museums, celebrating maritime past and slavery abolitionist Wilberforce, are being refreshed. Then there's the splendid Ferens Gallery with its Grand Canal by Canaletto. Add The Deep and there's more than you can do in a day.

Getting there

Hull trains (01482 606388; www.Hulltrains.co.uk) runs four services a day from London, connections at Grantham, Selby and Doncaster. Inclusive rail ticket and entrance to The Deep from £24.90. The Deep (01482 381000; www.thedeep.co.uk) opens daily 10am-6pm from March 23. Adults £6, children £4, family of five £18. Further Information: Hull Tourist Information centre 01482 223559.