On a dive to the wreck of the ill-fated Titanic, BBC Northern Ireland's environment correspondent Mike McKimm helped place a plaque to the hundreds who died in the disaster. The memorial from her home city comes 93 years after the liner left the slipway at Belfast's shipyard.
I'd glanced up at the tiny monitor above the Mir submersible's captain, heart racing.
Slowly, I began to pick out the shape of a ship's bow - a huge ship's bow.
Then, as the tiny Russian sub's lights probed into the jet black at the bottom of the Atlantic, an eerie shape loomed towards us.
It was unmistakable. We were floating just about 20 feet above the bow of Titanic.
The lights were trained on the ship and I began the five-hour job of filming the icon of all shipwrecks.
Even in the gloom and poor visibility, the wreck takes your breath away. It was huge and partly buried in the sea bed, having plunged there from more than two miles up.
Forty-six thousand tons, even broken in two, causes a massive impact when it hits the bottom of the Atlantic.
I was part of an expedition to place a plaque remembering those who died on the ship in the early hours of 15 April 1912.
It bore the message: "In memory of all those who died on RMS Titanic. From Harland and Wolff and the people of Belfast".
One of the crew in the tiny sub was Dublin diver Rory Golden. It was his second dive to the ship.
In 2000, he placed a memorial plaque from Cobh, Titanic's last port of call before heading out into the Atlantic.
The three of us were crammed into the tiny six-foot wide capsule of the 18-ton Mir.
Inside, at the surface, it was hot and humid but 12,850 feet down, it felt very cold and damp.
Turning to rust
Condensation dripped continuously from the unlined nickel steel shell. The secret was to distinguish condensation from a leak. The former is a nuisance, the latter, a warning of imminent disaster.
As we silently glided along, just feet above the ship's deck or followed her vast sides, one thing was apparent - Titanic was being eaten away by bacteria that were slowly turning the ship to rust.
It has become increasingly dangerous for submersibles to explore parts of the structure, and it's estimated that within 80 to 100 years, the top of the ship will have fallen into the hull.
Structures are already collapsing and chunks are falling off her. The bow was cluttered with all the equipment liners of her days would have had, such as winches, bollards, anchors and anchor chains.
But sprawled across much of it was Titanic's huge forward mast. Felled by the sheer pressure of water as the ship sank, it had started to collapse into itself.
A variety of plaques have been left to commemorate the victims
The small door from where a crew member saw the iceberg that was the ship's undoing was clearly visible.
The unpredictable currents at such depths are a real danger. They vary both in strength and direction.
They can even be vertical and push unsuspecting subs onto the wreck. We kept a respectful distance but as our mission was to lay a plaque on the remains of the bridge, we had to get very close at one stage.
The Mir's captain, Anatoly Sagalevitch, a veteran of many Titanic dives, inched us to the edge of the bridge and we adopted negative buoyancy.
This meant that the Mir went from weightlessness to weighing a few pounds. Using this to hold ourselves against the edge of Titanic, we began the long and delicate job of placing a small brass plaque alongside the other plaques already there.
It took more than 20 minutes. The plaque was held in an exterior basket at the front of the Mir. Using its manipulator, Anatoly lifted the plaque, snapping the small copper wires securing it during the dive.
Hit iceberg on 14 April 1912 - sank next day
Wreck lies about 365 nautical miles off Newfoundland
Sank in 12,850 feet of water
More than 1,500 passengers and crew lost
About 700 survivors
It was put in position but, because it was so light, it fell against the arm and toppled into the sediment on the bridge.
We tried again but this time it sank into the sediment while standing up.
We tried to clear the sediment but the plaque fell over again. But it fell silently. There was absolutely no noise.
Then, before Anatoly could lift it, the Mir juddered backwards. The movement of the manipulator arm and the currents had dislodged the sub.
We fell backwards, away from Titanic, into the dark. The thrusters whirred but in the dark, and with the sediment stirred up, we could no longer see the ship. Hearts raced again.
Then we nudged the side of Titanic and, using the thrusters, held the Mir there until the sediment cleared. It did this quickly - an indication of the strong current that day.
After a further struggle against the current, the plaque was put in place and we looked on silently.
It was then that it really hit home. This was a grave site - the resting place of some of the 1,500 people who were lost in the disaster.
The reason the bridge was missing was because it was torn off as the ship sank.
We drifted slowly past the other plaques marking the terrible loss that dark night 93 years ago.
Then we moved on to film the rest of Titanic. As we glided past the side of the ship, her size became apparent. She was enormous. The portholes and windows went on and on into the dark.
The dive was an emotional journey for Mike McKimm (left)
Our lights could not find the end of the forward part of the hull, even from half way along her. But they did bounce off the glass still in the portholes and windows. The light reflected back like a phantom in the ship walking inside her with a torch.
As we came to each porthole or window, the light flickered and was gone.
We soared past the circular holes where the funnels once stood. We circled around the officers' quarters and dived down to get a view of a white enamel bath exposed by the collapsing sides of the deck cabins.
It had been Captain Smith's bath. He died in the disaster and now here we were, staring at his private bath. At this depth it was unreal and created a slightly uncomfortable feeling of voyeurism.
We circled over the top of the ship to look at the Marconi Room. It was here that the radio operator stayed at his post sending out the CQD and SOS distress messages.
A single window with a white frame lay open. The roof of the Marconi room was full of rusting holes.
We slid past, just inches from it, and dropped back to the side of the ship, narrowly missing a lurching lifeboat davit.
But when we reached a gaping chasm that was once the grand staircase, I was transfixed.
The iceberg was first spotted from this mast door
We could see, but only just, down seven decks, deep into the bowels of the ship. It was just bent, rusting steel today but still demonstrated the sheer scale of Titanic.
Then on to the stern: sheared off in the sinking, it lay several hundred metres behind the main section.
The fracture looked as if someone had taken a French bread stick and wrung it in half. Twisted steel plates lay everywhere.
We hurried past this area, climbing for safety. The Mir pilots dread being caught in some lurking cable or steel structure.
The day after our dive, a Mir was caught by a steel structure and only escaped when the second submarine came to its rescue. They had to break off the structure protecting the back propeller to get free. Titanic is a dangerous place, especially around the stern.
As the ship crumbles away, parts of her, once hidden from sight, are now exposed to the camera. Two huge engine cylinders about seven feet across stood proud near her stern.
Crumpled piping was still fastened to them but the steel plates were twisted and tangled at the side.
The plaque is from the people of Belfast, where the ship was built
It took two and a half hours to get down to Titanic and about two hours to ascend. After more than five hours exploring we pumped out water ballast and began our slow climb to the surface.
In seconds Titanic was gone. The darkness reclaimed it. In the black of the Mir, with just the instrument lights illuminating the interior, we sat back, eating sandwiches and sipping warm, sweet Russian tea.
It was a chance to consider what we had seen.
Even weeks later, the Titanic is never far from one's thoughts. It was a huge visual and emotional experience to try to process, if indeed you ever could.