Late last year the phone rang in Keith Hurleys Chester home. On the line was an old friend, Colwyn Bay trawlerman Dennis Hunt.

The nets of Denniss boat, the Patricia Dee, had snagged on an object submerged off the coast of North Wales. Could Keith help out by freeing them

Keith, a member of the British Sub-Aqua Club and a keen, highly experienced wreck diver, was happy to oblige. Over the years his relationship with Dennis and other fishermen had borne fruit. Maybe, he thought, this uncharted obstruction would turn out to be something of interest. Little did he suspect that he would discover an important piece of maritime history.

The next day, Keith entered the water, followed the buoyed trawling cables to a depth of 18m, and paused. In front of him, a shoal of fish dispersed, and, in pretty good visibility, he made out a conical shape covered in rust and growth. At first he couldnt believe it. But as he drifted slowly over the 45ft hull, past the dented conning tower, and reached what remained of the propeller, he knew what he had found. This was definitely the wreck of the Resurgam, the worlds first practical submarine, which made her last - and permanent - dive in 1880.

It was an amazing feeling, says Keith. Shes one of those wrecks you hear and read so much about over the years. Thered been organised searches in the past, but I always felt that shed be found by chance. And now I was the lucky one.

You dream of making a find like this. I just looked at her and sort of double-checked. But there was no mistaking the Resurgam; the shape is just too distinctive. She was proud of the seabed, and I could identify features like the tiny portholes in the conning tower which are visible in contemporary photographs.

I placed my hand on her hull and thought, Im the first person to touch this sub in more than a century.

Keith surfaced and told Denniss son Jason, who was skippering the boat that day, that the nets had caught one hell of a fish - an ancient submarine missing since l880.

He didnt believe me, says Keith. He thought it was all a wind-up. But I kept on insisting it was true, so Jason brought the boat back over the site and there, on the echo sounder, was a profile which matched what Id been saying.

A shot line was put over the side, and I went down for another look. It was then that I found one of the subs portholes, lying inside the conning tower, having popped its rivets, and I brought it back up. It could only have come from the Resurgam. It was proof.

Back aboard, Keiths immediate reaction was to ring Dennis on the mobile to tell him of the discovery.

There was a stunned silence, says Keith. Hed got his nets back and found the worlds first submarine. It was like winning the Lottery. Keith Hurley took up diving in l979. Hed always been fascinated by the sea and its secrets, and when he met Peter Moore of Chester BSAC and heard more, he was inspired. Now he dives most weekends and sometimes during the week, in seawater or fresh water, at depth or in the shallows.

He has made a habit of finding valuable wrecks or items from known sites. There was the Oceanic, sunk in 1868, from which Keith raised a large cache of antique pottery; and the Royal Charter off Anglesey, one of his favourite wrecks, from which he recovered gold sovereigns and a 5oz gold nuggett. But the Resurgam tops his list. Its the history, that sense of discovery and exclusivity, explains Keith. Youre the first. You know lots of people have looked for her and many more have hoped theyd be the ones whod stumble on her. When it turns out to be you, well, its just great.

The Resurgam was the brainchild of the Reverend George Garrett, curate of Moss Side, in Manchester. Brilliant, somewhat eccentric, but also level-headed, he realised that submarines could police the British coastline and strike at any menacing Russian ironclads. He could safeguard his country - and make his fortune in the process.

His first submarine, often called the curates egg because of its shape, was a sort of Victorian X-craft. She wasnt much of a weapon, so Garrett thought again - and thought big.

The result was the Resurgam, 45ft long and weighing around 30 tons. Powered by a fireless steam engine, she carried three crew and was to be armed with recently developed fish torpedoes.

The submarine was constructed in 1879 by Birkenhead shipwright J.T. Cochran. Early trials went well, even though Garrett was forced to surface one day next to a passing schooner and ask the skipper for directions back to Liverpool. The captain took one look at the pioneering submariners and promptly told them: You are the three biggest fools it has ever been my misfortune to encounter. He had a point, for conditions on board the sub were nightmarish, including intense heat, tight space and difficult breathing.

Nevertheless, Garrett was sufficiently confident to demonstrate the Resurgam to the Royal Navy off Portsmouth. He resolved to steam there - an act of bravado salesmanship that would prove disastrous. Mr Cochran implored his client to transport the sub by rail, but Garrett wouldnt budge. Out in Liverpool Bay the propeller shed a blade, forcing Garrett to put in to Rhyl. For 16 weeks, repairs and modifications were made until at last, at 10pm on a February night in 1880, the Resurgam put to sea again. Now, though, she was under tow from a steam yacht, Elphin, which Garrett had bought to provide occasional comfort for the submarines crew. Disaster struck when Elphin developed engine trouble, the seas rose and the tow hawser snapped.

The Resurgams hatch, like that of any sub, could not be sealed from the outside. Stopped and rolling in the water, she was vulnerable to the sea, and it was not long before she filled completely and disappeared beneath the waves forever. At least that is what was generally believed. The submarines discovery may, though, throw a completely different light on her sinking.

I couldnt say for certain, says Keith, but the damage to her conning tower - a sharply V-ed dent - looked as if it could have been caused at the time of her sinking. It may well be that the tow rope broke in the night rather than the day, and that George Garrett, turning back to look for his pride and joy, rammed her in the pitch black and sent her to the bottom.

But Keith has an even more interesting second theory.

Apart from the sharp dent in the conning tower, I was very surprised to see that her main hatch had been removed - not ripped off, but clearly taken off. Also, the sub lies some way from the area where she might have been expected to be. It is my opinion that the Resurgam was deliberately scuttled; that, to save face, George Garrett had headed off for Portsmouth as if all was well - but that, knowing he had some problem with the sub, made sure that she never arrived. After discovering the Resurgam, Keith was surprised by the tidal wave of media attention that accompanied his find.

In the past, other finds had got me into the local paper, he says, but this was something else. The story broke at a weekend, and the phone calls and interviews didnt stop for a week. Dennis Hunt and I became quite a double act, telling our stories to BBC News, Granada, HTV, Radio 4, even to Canadian Broadcasting. You name it, we did it.

It was great fun and also confirmed that I was right in thinking that the Resurgam really is an important wreck - not just to me and other divers, but to all kinds of people.

Despite 116 years on the seabed, the Resurgam is in good condition, bar the dent in her conning tower and a hole in her bow. The prospects for salvage are clear.

That next chapter of the Resurgam story will hopefully be written soon. Several parties have expressed interest in raising, restoring and displaying the submarine to the public - including a theme park company which hopes to rotate the submarine around the many sites it owns across Britain.

Lying in just 18m of water, the Resurgam can be salvaged without too much difficulty. It is her preservation, though, which will prove complex and possibly very expensive.

I just hope that someone can find the money to preserve her and show her off to the public, says Keith. Shes a fascinating wreck, and the man who designed her lived an incredible life. As for where she goes, well, you can see why she might belong in North Wales, where she sank; or in the Royal Navys Submarine Museum in Gosport; or back on Merseyside where she was built and launched.

To my mind it doesnt really matter, so long as people have the chance to see her and discover what a Manchester vicar achieved way back in 1879.

I remember thinking, that day when I first clapped eyes on her, that youd have to be very brave, or very mad, or both, to put to sea in what was really an enormous boiler which travelled under water! But thats what pioneers do, I suppose. They risk things the rest of us might well avoid.

Diver magazine will report on developments in moves to salvage the Resurgam. Interested parties include the RN Submarine Museum at Gosport, Wirral Borough Council, The Historic Warships Trust, and Rhuddlan Borough Council.