September 1999: Theres a lot to think about when youre falling 93m into the Celtic Sea, down to the decks of one of the most famous shipwrecks in the world. While tremendously excited about the wonders waiting below, the mind must still concentrate on making a safe descent.
Whether using the revolutionary closed-circuit or the plain old-fashioned open-circuit approach, the key tool when diving to such depths is mixed gas. For dive partner Chris Hutchinson and me, rebreathers are not an option today.
Dropping through our first switch depth at 30m, we begin to breath a mixture of heliair 11/47, concealed within our back-mounted twin 20 litre cylinders. The new gas mixture will see us safely along the decks of the wreck, but before we descend any deeper, we spare a moment to isolate our previous gas supply of nitrox for the return journey.
Dropping deeper through the 30m thermocline, unpredicted Atlantic tidal currents around the Old Head of Kinsale bless us with 5m of visibility. Weighing 32,500 tons and 238m long, the Lusitania is big, deep and, after considerable collapse throughout, complicated.
As darkness descends, we fire up 200 watts of light between us. For the next few minutes, eyes adjusted, we secure the anchor line for others to follow.
This is our first dive on the old liner and we find that slightly astern of the bridge makes a good place to start.
With the shattered state of the wreck, you could count on one hand the number of divers who know their way around the whole site. We have no positive destination on this occasion, so we move off in the direction of midships and the stern. We find an area of covered mosaic-tile flooring in the vestibule located in first class accommodation, at the point where passengers would have entered from the boat deck.
Further along, and immediately beyond the first funnel void, are three main freshwater tanks, still in their original location, the working valves readily recognisable.
My attention is distracted by a flash from Hutchs torch. He has found a rare example of a tropical porthole. The small vents above the window would once have allowed a constant flow of fresh air through a humid first class cabin, while internal clack valves would prevent water entering during rough sea conditions.
A small amount of netting needs to be removed before we can photograph this unusual artefact. But it is only the start of things to come, for wherever you turn on the Lusitania, you are confronted by early 20th century affluence.
This quiet section of the Celtic Sea is nirvana for wreck-divers.

May 1915: For Kapitanleutnant Walter Schwieger of U-20, the end of another exhausting Atlantic patrol was tantalisingly close. With only two torpedoes left, and oil supplies uncomfortably low, U-20 turned her nose into the thick fog and headed for Wilhelmshaven.
In terms of the deadly global chess match going on, the 30-year-old German submarine commander couldnt have run a more fateful course had he tried.
Three months before, Germany had announced a blockade of the British Isles. Merchant shipping entering the war zone would be sunk, if necessary without warning. Schwiegers course and that of the Lusitania were now converging.
At 3.10 on the afternoon of 7 May, U-20 fired a single torpedo from a distance of 700m. In the devastation that followed, 1195 lives were lost.
British newspapers reported the sinking as an outrage against humanity and a blatant disregard for the rules of warfare, but U-20s single torpedo had produced an unexpected dividend for Britain and her allies in the propaganda war.
What was regarded as a brutal German war crime galvanised public opinion and ushered the USA into war. The incident signalled the beginning of unrestricted U-boat activity in the Atlantic.

February 1995: For all the years that the Lusitania has been on the ocean floor, it has been at the centre of controversy. Conspiracy theorists have pointed to supposed contraband carried below decks, others have speculated about the value of precious metals and jewellery aboard. There have been a number of accusations of attempted salvage cover-ups, and courtroom battles over ownership.
It has been claimed that Sir Hugh Lane, the director of the National Gallery of Ireland who was lost during the sinking, had with him on board paintings estimated at $60 million, including works by Rubens, Titian and Monet.
According to one rather far-fetched story, Lane had a premonition of disaster and had the paintings shipped within special sealed lead and zinc tubes to protect them from the perils of the sea. After speculation that containers matching this description had been seen on the wreck, the Irish government took the situation seriously enough to ban diving at the site entirely in 1995. Using the National Monuments Act, Minister Higgins placed a heritage preservation order on the site, the first of its kind on a shipwreck under 100 years old.
Irish, British and US courts recognise 71-year-old Gregg Bemis Jr, chairman of Deep Ocean Engineering, as the owner of the Lusitania, its fixtures and fittings, though not of its cargo or any personal possessions that might be found.
Bemis says that a crate from Lane is listed on copies of the manifest for the Lusitanias last voyage, though he adds that the entry could have been added later. But there are no marks on the manifest indicating receipt of the crate or where it would have been located.
No comment, was the response Bemis received when he asked whether the Irish government had researched the lost paintings following the preservation order. But if such works were aboard, and they are ever recovered in acceptable condition from the Lusitanias resting place in Irish waters, their future could be a matter of contention.

September 1999: Its the second day of diving for the 99 expedition team, and we continue to focus our efforts around the bridge. Project leader Mark Jones was one of the first to obtain a licence to proceed with diving since the heritage preservation order banned it four years earlier. Supported by O-Three, C-Bear and Custom Divers, he has put together a team of exploration divers - Nichola Thompson, Kevin Emans, Alex Vassallo, Geraint Ffoulkes-Jones, Richard Stevenson, Chris and myself - with a support team consisting of Mark Leman and three others who will also dive the wreck, Helen Finn, Oliver Dicketts and John Mayo Evans.
Also aboard our support vessel is Gregg Bemis, who has flown from New Mexico to oversee operations on his wreck, while deep ocean explorer Robert Ballard has arrived to do some filming.
The journey to the wreck from Kinsale harbour takes more than two hours. A naval frigate is standing by to observe us. The day before, we had been boarded to have our licences checked, and throughout the week we would see officials from the Heritage Department and be paid regular visits by the Irish Receiver of Wreck, Jerry Greenaway.
Chris Hutchinson and I make our way down the anchor line and, once on top of the wreck, secure a strobe to it to help us find our way back. We intend to follow the 30 list of the existing decks down to the seabed and photograph the remains of the bridge lying out across the bottom.
On the previous dive, Richard had used his Buddy Inspiration rebreather to give him a 30-minute bottom time and cover quite a distance along the seabed debris field at 93m. Reaching our first stop, a first class bathtub and shower fixture, is made easier by the guideline he left. Now we leave it and, in 6m of visibility, make our way across the remains of the bridge.
This area of the wreck is wonderful, for whichever way we turn there lie even more fascinating artefacts.
Fine examples of early 20th century navigational equipment rest quietly on the seabed. A telegraph lies on the ships telemotor, both in excellent condition and unattached. Half-buried in the sandy bottom, and not a stones throw from the telemotor itself, lies a whistle.

The Lusitanias other whistle was recovered in 1982 and sold at auction. The ships bell, also recovered at that time, is said to have been sold for£50,000 to somebody living in Wales.
The following day is spent exploring the bow, one area of the wreck that remains quite recognisable. Much of the winch gear remains in reasonable condition, as do capstans and the decking on which it all rests.
At a higher level on the port side of the bow, at a depth of 82m, we pinpoint the brass letters spelling out the ships famous name. Although reasonably covered in marine growth, some of their outlines are still distinguishable.
A lot of net is draped over the wreck from here onwards, so we drop under the starboard side, where a huge anchor remains housed in its original position.
Having used almost 25 minutes of bottom time, and with viz down to 3-4m, we make tracks back beyond the bridge to pick up the line home.
Visibility increases dramatically at shallower depths, where the free-floating decompression station, made up of components used by several members of the team on the previous years Britannic expedition, awaits. Only after an almost three-hour deco penalty will we surface to enjoy a brew. But our surface support team are kept amused by the wonderful presence of whales and dolphins swimming in the area.
For the rest of the week, Chris and I spend our limited but precious time slowly and comfortably working our way through the collapsed covered promenade and boat decks, photographing as we go. For every porthole and square window we see in place, each with its individual Edwardian trim of ornate filigreed detail, an equal number lie scattered, their iron fasteners having corroded until they fell into the debris field.
Towards the end of the week, heritage officials agree to a sample of the hull plating being lifted. It contains a number of wrought iron rivets; the hull was made entirely from sections of large plates held together by these, so forensic analysis could give an idea of its strength, and the Lusitanias remaining lifespan.
I ask Gregg Bemis what will happen to the artefacts that litter the site. He says his long-term project is to restore and preserve them to help educate future generations - an idea with which, if it is to happen, the Irish government will need to agree sooner rather than later.
The Lusitania is one of the classic dive sites of the Northern Hemisphere, and some day Bemis would like it to be open for all divers to explore. That will not, however, be the governments aim until it is sure there are no lead or zinc tubes to be found among the wreckage. In July we return to the site.

The initial travel gas and first deco gas, nitrox 35, was chosen as it gave a good deco profile. Thirty-five per cent oxygen also roughly balanced the quantity of gas required for the two side-mounted cylinders (the other being nitrox 70) balanced in 10-12 litre cylinders on each side. It also avoided a large helium-to-nitrogen swing, which is typical from deeper switches to air.

The bottom gas of heliair 11/47 was chosen as it gave an END (equivalent narcotic depth) of 35m and a ppO2 of 0.94 bar at the absolute top of the Lusitania, and 45 m and ppO2 of 1.13 bar on the seabed in the debris field (93m), where most of the dives took place.

The low bottom ppO2 (nearer 1 bar than 1.4 bar) enabled higher oxygen percentages to be used during decompression, while keeping the overall CNS (central nervous system) clock below 100 per cent for bottom times up to 25 minutes. The deco schedules also included times that would get the divers out of the water using only 70 per cent in the absence of O2.

Oxygen (that is, zero inert gas) on the final stop was important, especially on repeated deep dives. A 5m break on nitrox 35 was inserted following every 25 minutes on oxygen.