It's been almost five years since the Rena ran aground on the Astrolabe Reef. It was desribed as the worst maritime environmental disaster in New Zealand, and one of the world's most complex clean-ups.
Waikato University marine ecologist, Dr Phil Ross, has just published research on the environmental effect of the shipwreck.
He's done more than 100 dives at the Rena site over the past four years and photographed the undersea world around the wreck.
His first dive was a year after the ship grounded in 2011, and his most recent just this week. He said it had changed incredibly during that time.
"The first dive was a sensory overload. It's a huge ship, you're in the water and you can hear the creaking, groaning of everything rolling around."
In subsequent dives he found so much metal and cargo.
"Imagine if you went to a scrap metal yard then transposed that to an underwater scene, that's the sort of thing you're seeing.
"There was nothing alive under the giant pile of metal."
A lot of work had gone into the wreck in the years since and a lot of the scrap had been removed, he said.
"The areas that were formally covered in debris are starting to be recolonised.
"Apart from the odd piece of metal you wouldn't even know there was a shipwreck there."
There's now about 25 boats visiting the wreck each day, since the cordon was lifted earlier this year.
Dr Ross expected it would be a popular tourist attraction in the future.
