They raced to stop the oil spill. The island's pristine coastline may be beyond help.

MAURITIUS — Within minutes of hearing about the oil spill, David Sauvage raced to the waterfront.

The MV Wakashio, a Japanese-owned ship heading to Brazil and carrying an estimated 4,000 metric tons of oil, ran aground on Mauritius’ southeast coast on July 25.

Tons of oil have gushed from cracks in the vessel, streaking the island's turquoise water black and threatening to ruin its coral reefs, protected lagoons and shoreline.

Sauvage, an environmental activist, wasn’t confident that officials in this Indian Ocean island nation would act in time to protect the pristine coastline for which it's renowned.

So along with members of a local political party he worked through the night, using a net stuffed with dried sugarcane leaves in an effort to prevent the oil from flooding the island.

“Low-cost, low-tech, readily available materials that soak up oil,” Sauvage told NBC News.

The group busied itself making more of the "booms" and word soon spread. The next day thousands of Mauritians across the island had gathered to craft the natural barriers.

Hundreds more donned gloves, masks and other personal protective equipment and plunged neck-deep into the oil, cleaning the mangroves and ocean as best they could.

The volunteers have ignored a government order to leave the clean-up operation to local officials, potentially risking a fine or other punishment. NGOs asked volunteers on Tuesday not to risk their health cleaning up the oil on the coast but to concentrate on boom-making instead.

High winds and waves are pounding the Japanese bulk carrier, which is showing signs of breaking up and dumping its remaining cargo into the waters surrounding the postcard-perfect island off the east coast of Africa.

Nearly 2,000 metric tons of oil, diesel and petroleum lubricants could inundate the lagoon if the Wakashio breaks apart, and experts believe it’s a matter of hours.

“The situation is very critical. Cracks have expanded over the course of the day,” said Dr. Vassen Kauppaymuthoo, the island’s premier oceanographer.

“The situation’s about to get 10 times worse. It’ll be a major catastrophe,” he said.

The oil is traveling up the coast, Kauppaymuthoo told NBC News, which could lead to huge stretches of lagoon being affected.

“It’ll take decades to rehabilitate the lagoon, and it’ll never be as it was before the spill. We have thousand-year-old coral here, protected species in our waters,” he added.

“I’m so sad, so angry. Larm koule,” he said in creole. The phrase means "tears run down my face."

Tourism has long been at the heart of the country’s economy, with a string of luxury hotels punctuating every coastline.

The country had emerged from the restrictions of the COVID-19 pandemic two months ago relatively unscathed, with only 344 total cases and 10 deaths, according to Johns Hopkins' Coronavirus Resource Center. The government recently launched a fresh series of tourist campaigns in an effort to revive business.

But now schools in the region have been closed because of the overwhelming smell of petrol and dead fish that permeates the air.

There’s concern that residents near the coast where the ship is stranded, among several sites of great ecological importance, may have been exposed to hazardous substances washing ashore.

“I can’t smell it anymore,” said Sauvage, who has barely left the waterfront since the spill.

Prime Minister Pravind Jugnauth has declared a state of emergency and appealed for international help. He said the spill “represents a danger” for the country of 1.3 million people.

Japan on Sunday said it would send a six-member team of experts to assist. French experts have arrived from the nearby island of Reunion.

But pressure is mounting on the government to explain why it did not act sooner to avert the environmental disaster.

The opposition and activists are calling for the resignation of the environment and fisheries ministers.

“We’ve seen the trailer but not the movie yet, of the crisis to come,” said Dr. Vikash Tatayah, director of the Mauritian Wildlife Foundation.

He’s been leading rescue efforts on Ile aux Aigrettes, an islet central to conservation efforts, evacuating species of plants and animals to safety.

The oil has encircled the islet like a noose.

“It’s a disaster,” Tatayah said.

“Never in my wildest nightmares would I have imagined something like this.”