Transcript
Late afternoon at Muri lagoon... it's hot and the water's still. People are lolling in the shallows and lounging on the beach.
Richard Smith, a tourist who's just arrived on Rarotonga, has no idea the lagoon is in trouble.
"It's a peaceful lagoon and I'm not too strong in the water so it's about my speed and it's sheltered and you can snorkel right off the beach. This is perfect for us."
It was also news to another visitor Hamish Whistler who's just been out snorkelling.
"It's actually not looking too bad. There's a bit of bleaching. There's still a lot of marine life but it's kind of concentrated in the last live bits of coral. It does look like it used to be a lot better but you can see a bit of the bleaching and that and dead coral floating around. I was hoping it'd be better than this but it wasn't bad."
Graham Taylor who lives near Muri and regularly walks his dog there says it's far from the pristine place it once was.
"I think it's the colour, there's a smell about it sometimes. If you dig deep into the sand, there's sludge down the bottom - blue, blue sand, never seen blue sand before. Because it's all the sediment that's sitting on the bottom of the water. There's a big problem here and they've got to do something about it."
A bloom of algae has spread through the tourist hotspot since late 2015.
A cocktail of factors is thought to be responsible ... seepage from septic tanks, a high density of hotel rooms, run-off from farming, high temperatures and a heaping up of sand and rocks in the lagoon outlets.
Kelvin Passfield of the environmental group, Te Ipukarea Society, says it's not deemed a health risk, but he doesn't swim there anymore.
"I'd say it's very close to dying. If you go for a snorkel out there and look at the coral heads, there's a few small areas where there's still live coral. So much of it is just dead now and a recent bleaching event, we've just had a coral bleaching event which hasn't helped."
The Asian Development Bank noted the pollution back in 2009 and warned then of the risk to the critical tourism industry.
A traditional leader near Muri, Philip Nicholas, says his people and fishing are affected too.
He says drastic action's needed now.
"If we can get in there and remove all that sand, dredge that sand out, we should see an immediate improvement in the flushing of the whole lagoon from Muri down to Avana."
Kelvin Passfield says dredging is a short term solution.
"One of the issues is that there are still being approvals given for more resorts and hotel developments on the coast and that's just going to exacerbate the problem. The more nutrients going in is just going to make it worse and they should be looking very closely at restricting more hotels going up."
He says scientists and engineers need to give a comprehensive report, come up with a design for a better sewage system and that landowners need to get on board.
"The chance of recovery is slim without some real intervention and then rehabilitation later on to bring it back but I think the short term outlook is not good at all."
Over the last fortnight the seaweed is reported to have died off a bit because of plenty of rain.
The CEO of the Cook Islands Tourism Corporation Halatoa Fua is optimistic, citing a new cohesive approach to dealing with the bloom, and consultants have been engaged to come up with a solution within 18 months.
"It's one of the most photographed and visited sights in the Cook Islands especially for visitors but now that we've seen a lot of that disappearing it's quite pleasing for us but it doesn't mean that we rest on our laurels. There still needs a lot of work to be done for sanitation management here in the Cook Islands."
Philip Nicholas says there've been too many consultants reports and not enough action.
"It's a living issue. It's in my arteries and in my veins. My connection to the sky, to the mountain, to the lagoon, the rivers to the lagoon and the vast ocean. It's a living thing to us so I want to see this work."
Back on the shore of Muri lagoon, Canadian tourists Richard Smith and Barbara Gibson suggest tourists could be part of the solution.
RICHARD SMITH: "We'd be happy, I think, to pay some sort of you know environmental clean-up tax. So here's the room bill, here's how ...
BARBARA GIBSON: ... how you're contributing to help.
RICHARD SMITH: Exactly. If that money went to it, then I think every tourist would be happy to contribute to that."
Cabinet minister Mark Brown says fixing up the lagoon is a priority and dredging work is likely once environmental consents are achieved.