From the shores of the Indonesian island of Bangka, miners like Hendra travel by boat every day to a fleet of crudely constructed wooden pontoons off the coast, equipped to dredge the seabed in search of lucrative ore deposits. tin.

Indonesia is the world’s largest exporter of tin used in everything from food packaging to electronics and now green technologies.

But the deposits in the Bangka-Belitung mining center have been heavily mined on land, leaving parts of the islands off the southeastern coast of the island of Sumatra resembling a lunar landscape with vast craters and very turquoise lakes. acids.

The miners turn instead to the sea.

“On earth, our income is declining. There are no more reserves, ”said Hendra, 51, who started working in offshore tin mining about a year ago after a decade in the industry.

“In the ocean there are many more reserves.”

Often clustered around underwater tin seals, the dilapidated pontoon encampments emit plumes of black smoke from diesel generators that rumble so loudly that workers use hand gestures to communicate.

Hendra, who uses a name like many Indonesians, operates six pontoons, each manned by three to four laborers, with pipes that can be over 20 meters (66 feet) long to suck sand from the seabed.

The pumped mixture of water and sand is conveyed over a bed of plastic mat that traps the shimmering black sand containing tin ore.

Hendra is one of dozens of artisanal miners who are partnering with PT Timah to exploit the state’s mining concessions.

Miners are paid between 70,000 and 80,000 rupees ($ 4.90 to $ 5.60) for each kilogram of tin sand they pump, and a pontoon typically produces around 50 kilograms per day, Hendra said.

Timah has increased production from the sea. Company data shows its proven reserves of tin on land were 16,399 tonnes last year, compared to 265,913 tonnes offshore.

The huge expansion, coupled with reports of illegal miners targeting offshore fields, has exacerbated tensions with fishermen, who say their catches have collapsed due to the constant encroachment on their fishing grounds since 2014.

Fisherman Apriadi Anwar said in the past his family earned enough to pay his two younger siblings to go to college, but in recent years they have barely scratched.

“It doesn’t matter whether you go to university, nowadays it’s even difficult to buy food,” said Apriadi, 45, who lives in Batu Perahu village.

Apriadi said fishing nets can get tangled in offshore mining equipment while trawling the seabed for ore veins that have polluted once pristine waters.

“Fish are becoming scarce because the coral where they spawn is now covered in mud from mining,” he added.

Indonesian environmental group Walhi has campaigned to stop offshore mining, especially on the west coast of Bangka, where mangroves are relatively well preserved.