Crucial kelp restoration is underway in Whakaraupo, Lyttelton Harbour, to restore what the ocean there has lost.

The project, funded by Live Ocean, the NZ Sail GP charity partner, sees local scientists collaborating to help revive the languishing ecosystem there.

Above the water Lyttelton Harbour is a sight to behold, but beneath the surface, the state of the kelp forests bring tears to Mara Moana Project leader John Kottier's eyes.

"It's horrendous, I mean it conjures up all sorts of emotions, it's terrible."

That's why he's leading a a Ngati Wheke dive team, as they rid the area of Undaria, an invasive and undesirable kelp, so it can be replaced with Rimurimu, a native giant kelp.

It's a process developed by scientist Matt De Roe in an Otago University Laboratory.

"My hope is to get back to the way some of these ecosystems used to be. We take this product which produces spores back to the lab and this is what we culture to bring back and reseed into the kelp beds," he said.

In the summer of 2018 a marine heatwave wiped out the bulk of native kelp in Lyttelton Harbour, and four years later it still hasn't regenerated on its own.

Kottier says: "I have memories of what it used to be and it's really to return that back even if we got somewhere near what it used to be."

Live Ocean is helping make it happen with funding from New Zealand Sail GP team wins. NZ Sail GP sailor Finn Henry says: "As much as we love competing and chasing the victory for the Sail GP, I think it's an opportunity to do something more long lasting and for the future."

Live Ocean CEO Sally Paterson says the role of kelp shouldn't be underestimated: "The ocean is changing really fast and kelp is a hugely important part of a healthy ecosystem.

"It's home and food for marine life and hugely efficient in dealing with carbon in New Zealand. I think we need to start thinking about our kelp forests as our coral reefs."