THERE'S A LOT TO THINK ABOUT when youre dropping 120m into the Pacific Ocean, down to the decks of one of the most famous shipwrecks in the world, the Royal Mail Steamship Niagara.
While tremendously excited about the wonders waiting below, I have to concentrate on making a safe descent using my closed-circuit rebreather.
Whether using CCR or old-fashioned open-circuit, the key tool is the mixed gas. I am breathing a HeliAir mixture of 7% oxygen, 67% helium and 26% nitrogen.
At 30m, my computer automatically adjusts my oxygen control set-point to a higher partial pressure of oxygen. I hear the solenoid kick in and fire the correct amount of gas into my breathing system.
I drop deeper, through a thermocline. Unpredicted Pacific tidal currents around Bream Head in Whangarie, on the North Island of New Zealand, will make finning around the wreck a little difficult.
I drop beyond 100m, fire up 100 watts of light, and the wreck comes into view. At 13,415 tons and 165m long, Niagara is no small wreck. I arrive at the bow tip, where our anchorline has hooked close into the seabed.
The teak decking is well preserved. Mooring bollards appear out of the gloom, as do capstan winches, anchor chains and cargo booms.

THE WRECK LIES ON ITS PORT SIDE, with a light covering of marine growth unique to the area. Finning along the bow deck, I see a broken mast overhanging and disappearing across the seabed at
a right angle. In the distance are the flashing lights of other divers and the sounds of unknown activity.
Minutes pass as I make my way past the bridge superstructure, where wonderful square Georgian windows are silhouetted by blue ocean behind them.
Down at seabed level, my gauge reads 121m. I begin to photograph the remains of the bridge navigational equipment that has fallen from above. I cant help thinking that somewhere among this wreckage are bars of the gold that the Niagara was secretly carrying when she sank.
After some 35 minutes I retrace my path and arrive back at the anchorline. Ahead of me lies some six hours of decompression beginning at 90m, a vast penalty to pay for the privilege of swimming the decks of the ocean liner known as the Queen of the Pacific.
At 60m I reach a line junction, leave the anchorline and proceed to a decompression station released from the main downline and allowed to free-float with the current. It provides a considerably more comfortable decompression phase for the divers.
During deco, I hear calling noises from above. Australian divers Craig Howell and Richard Harris are waving their arms and looking triumphant. They should be. They have just located the ships main mast bell, the heart of the Niagara.
For 67 years this ornate bell has lain silent on the seabed. Now the divers have carefully sent it back up. On the decks of the dive vessel Perfect Day, the Dive Tutakaka boat crew look on in disbelief. Theyre the first people to see this artefact in almost seven decades. Friday 30 March, 2007, really was a perfect day.

NIAGARA WAS DESIGNED by Coll McDonald of New Zealands Union Shipping Line and built by John Brown & Co in Clydebank, Scotland to the highest of standards - equal to the great contemporary ocean liners such as Lusitania and Mauretania. Launched in Glasgow in 1912 she was christened the Titanic of the Pacific until that ship sank later in the year. Niagara soon became Queen of the Pacific.
Her maiden voyage in 1913 saw her make passage between Sydney and Auckland via the Pacific islands and on to Vancouver. Over 27 years she would cover more than 2.295 million nautical miles, an ocean liner record that still stands today.

ON 19 JUNE 1940, Captain Bill Martin brought Niagara north to Bream Head from Auckland and retired to his cabin for the night, unaware that his ship was heading into the path of a minefield laid by the German raider Orion.
New Zealand, as a Commonwealth country, was part of the war in Europe. This was no ordinary voyage for the captain or his crew. Unknown to many aboard, Niagara was carrying eight tons of gold bullion destined for Canada. In Vancouver it would pay for arms in Britains struggle against the Nazis.
At 3.30am there was a huge blast. Mortally damaged by a mine, Niagara began to settle by the head, developing a list to port. Amazingly, all 148 passengers and 203 crew transferred to the lifeboats.
By 5.30am they were watching in disbelief as their ship slipped beneath the waves, striking a second mine as she sank.
Niagara might have been forgotten had it not been for those gold bars. Valued at 10 million in 1940, that would translate to 200 million today. The Bank of England wanted their gold back, and what followed was one of the most famous gold salvages in history.
A crew led by Captain JP Williams assembled aboard a decrepit coaster named the Claymore, and spent two months in the minefield looking for the wreck. Once it had been located, they searched for the gold using a purpose-built observation chamber lowered to the wreck. A diver inside could communicate with the surface crew and guide them in manoeuvring a grab into place.
The gold was locked deep inside a reinforced steel strong-room within the bowels of the wreck. The ship was systematically dissected to expose the bullion room, then the grab went to work.
All but a few bars were recovered during the 1940s, setting new records for gold recovered from depth, alongside the famous ss Egypt wreck salvage of 10 years before (DIVER, October 2001).
Of course, the remaining gold has been the subject of conversation around the port of Tutakaka for years. The story is told in Keith Gordons book Deep Water Gold and Keith, a Tutakaka resident, has been involved with the wreck for many years. He joined the NZTech07 dive team to assist with the historical research.
Technical diving on Niagara began when Tim Cashman, a Welshman living in New Zealand, made a routine dive trip to the sub-tropical Poor Knights islands. Lunching at the local game-fishing club, he noticed pictures on the wall of the 40s gold recovery and, intrigued, set about locating the wreck, travelling up from Auckland in his small sailing boat.
On 26 January 1999, Cashman and his Australian dive partner Dave Apperley became the first men to swim the decks of the old liner. Since then the two divers have joined almost every expedition to the wreck, including this latest one.
For NZTech07 divers, a scuba exploration attempt on the Niagara was considered a serious team undertaking. The success of previous expeditions centred on team effort based on safety first, which gave Melbourne-based expedition leader Craig Howell plenty to think about.
The first dive was from Pacific Hideaway, a vessel that many previous Niagara expeditions had used. After that the team operated from Dive Tutakakas new dive platform Perfect Day. Twenty-three man-dives would be carried out, equal to the total number of dives carried out since Cashman and Apperleys original foray, making this expedition the most successful to date.
The first dive of the expedition was a bit of a let-down at first because of the unexpectedly poor visibility, though this didnt stop the nine-man dive team undertaking a full exploration.
As I arrived at the wreck at about 110m I could see that the anchorline had dropped off the underside of the hull and was lying with the current across the bulk of the hull, securely fixed by the first team down. I was just aft of the bridge, on the uppermost, starboard side.
After adjusting my strobe-arms and the settings on my deep camera system, I dropped deeper and crossed an open deck hatch with its intact coaming. The low vis was not aiding navigation, so I swam steadily down to the seabed and made my way alone towards the bow section.
It was here, directly below where the wooden construction of the bridge would have been, that I discovered the complete navigational instrumentation among the wreckage. I counted five reasonably large telegraphs. These had once signalled requested ship movements to the engine-rooms and stern.
I also saw the telemotor, the huge hydraulic steering system that powered the rudder when the ship was moving at speed, and an annunciator, an instrument that relayed information on the turbine engines to the bridge.
The area was of amazing interest, and for the rest of my short bottom time I became absorbed by photography, before making my way to the uppermost sections of the wreck, with more of those Georgian-style windows marking what remained of once stately rooms.
As rays of light poured though the windows, I realised how privileged I was to see this wreck. My 35 minutes at depth meant another six hours decompression, and a beer at the local Snapper Rock bar that night was more than welcome.

AFTER THIS INITIAL DIVE, bad weather hampered the teams operations, so we prepared for the next dive and went off
to enjoy the delights of the Poor Knights Islands with Dive Tutakaka.
Then came a torrential storm, with more than 48 hours of rain and landslides that cut off Tutakaka from Whangarei and surrounding towns.
It was the biggest rainfall in New Zealand for 20 years, and the sea storms delayed any further diving on Niagara. But in improved weather the last dives of the expedition were exceptional, and team-leader Craig Howells recovery of the ships bell made the news headlines across New Zealand.
Australian Richard Harris recovered a bridge telegraph and fellow-countryman John Dalla-Zuanna the Walkers log, an instrument that would have indicated speed and distance. The artifacts are being preserved and are expected to go on permanent display in New Zealand.
By the last dive, the team really had a feel for the wreck and its condition.
The anchorline remained in a position towards the bow tip from the previous days dive, when the bell had been discovered, and on this last dive I left the line and swam hastily to a position beyond and aft of the bridge, where my last exploration had terminated.
I was looking at the entire midships section of the wreckage, with lifeboat davits lying across the seabed alongside hatch covers, fallen portholes and square windows.
I discovered the area where the forward funnel once lay across the seabed - and here I found Niagaras huge chime steam whistle, once her calling sound as she entered ports around the world.
The entire dive experience was very special for the whole NZTech07 dive team. Niagara was once again left to lie with her several unaccounted for bars of gold still hidden - until perhaps the next team makes the find of a lifetime.

Leigh Bishop
Craig Howell begins the recovery of the ships bell.
Craig Challen with his twin Megaladon closed-circuit rebreather set-up on the decompression station.
Andrew McIntosh examines a classic Georgian window in the lower bridge section of the wreck.
The salvage team during World War Two, with gold from the Niagara.
Mooring bollards on the bow deck.
The main forward-mast crows nest.
One of five telegraphs that can be seen around the bridge.
Richard Harris, the expedition doctor, prepares to dive the wreck.
Tim Cashman looks at a staircase entrance on the bow section of the wreck.
Craig Howell was a very happy man to have his hands on the Niagaras bell.
Tim Cashman, the man who triggered technical diving expeditions to the Niagara and first dived it in 1999.
The dive team aboard Perfect Day with the recovered ships bell.