It is pitch black except for the odd generator-powered light, just a faint glow amid the gloom.
The smell - a putrid mix of salty air, heavy-fuel fumes and thawed, rotting food spilled from broken containers - is almost overpowering.
And the noise is terrifying.
The sound of howling wind and crashing waves combines with a cacophony of creaks, bangs and groans of steel grinding on steel.
These are the death throes of MV Rena, one of the most perilous wrecks a world-renowned team of salvage experts has seen.
Weighing heavily on the salvors' shoulders is the need to pump away all of the oil still in Rena's tanks before it breaks up. But first, they must empty one port-side tank and then try to get to the 356 tonnes in the tank on the other side.
With a five-day window of fine weather and a booster pump that cleared 171 tonnes by yesterday afternoon, there is optimism, but the job is dangerous.
"Everywhere, there's risk at the moment," Svitzer salvage company master captain Drew Shannon said.
"It's not like working on ... a normal ship. The ship is listing. It's creaking and groaning. The whole ship is an area of concern, clearly."
The most dangerous area was the ship's starboard side, where the deck was covered with water and piles of containers were listing sideways.
"That's a place we are not working. Especially when it's high tide. There's waves coming over the side and you can definitely see there's water on deck."
Mr Shannon said salvors were working in areas where danger levels had been well assessed.
"We do become attuned to it and it does take time. They've all had the training on how to deal with these situations, but there are concerns, and we have vessels on standby."
In the engine room, where the situation is much more stable than a week ago, salvors worked in pairs for safety reasons.
There, water had been pouring in from a starboard manhole. Divers were sent down to check it as salvors prepared a cofferdam - an enclosure to keep water out - to access the starboard tanks.
"No two jobs are the same and each has its challenges. So we have to adapt to the conditions and the needs of the casualty.
Maritime New Zealand salvage unit manager Bruce Anderson has been aboard Rena and knows what the salvors are up against.
"These guys love challenge and enjoy trying to understand the issues, but even they're saying it's the toughest job they've ever had to do. It's complexity upon complexity upon complexity."
Svitzer spokesman Matt Watson said: "When you are up close to it, it sounds like Jurassic Park you hear this groan, and then a crack, and then a roar like she's kind of writhing in the water.
"It runs from one end to the other and then it just seems to ricochet back." He saw the stricken ship as a lame, dying beast. "It's like the ship is trying to talk, saying 'help me, get me out of here'.
"She is a very sick and distressed creature, and it's almost as if she knows she's got these salvors crawling all over her, and she's crying."
