Being in the middle of the Indian Ocean at night is incredible: the vastness of the sea around you, the raw power of the waves, and the thick darkness.

Now imagine from miles away, you see a glowing mass on the horizon. As you get closer you make out the source: intense beams of light from an array of approximately 80 high-powered lamps, searing into the water all night long. Marine life is teeming under the surface, drawn to the brilliance of the light.

Supply Vessel Explorer II in the Indian Ocean © Will Rose / Greenpeace

The Explorer II is a vessel thought to habitually use some 80 high-powered lights to aggregate fish in a potential breach of marine regulations. © Will Rose / Greenpeace

That’s what we found when we encountered the Explorer II, an ominous-looking vessel in tuna giant Thai Union’s supply chain. It’s not like any ship we’d ever seen, and its lights seem to only have one purpose: a controversial method used to attract all kinds of ocean animals before other fishing vessels come and set nets around the lot.

That’s right: everything.

Activists on board the Esperanza have been out in the Indian Ocean for over five weeks cleaning up Thai Union’s supply chain; tracking and removing destructive fishing gear which plays the same role as the Explorer II. Marine life gathers underneath the gear and then ships come and set their nets around it. But the Explorer II is a whole new scale of operation and the potential for overfishing and indiscriminate harm to marine life is huge.

The supply vessel Explorer II in the Indian Ocean. © Will Rose / Greenpeace

The supply vessel Explorer II in the Indian Ocean

Unlike other ships, the Explorer II doesn’t move around. It anchors itself to one spot – we’ve repeatedly found it using the underwater Coco de Mer seamount north of the Seychelles – so fishing vessels know where to find it. Then it just sits there, beaming light into the water to attract fish.

With the help of citizen research by supporters in the UK, the Netherlands, France, and Italy, we know that this ship’s Spanish owner, Albacora Group, is supplying Thai Union and its European brands including John West, Petit Navire and Mareblu.

And what we’ve found points to the Explorer II likely engaging in reckless fishing practices – the kind that are killing marine life indiscriminately, driving overfishing by emptying our oceans and robbing local fishing communities of their livelihood.

Activists Confront Supply Vessel Explorer II in the Indian Ocean © Will Rose / Greenpeace

Greenpeace activists peacefully confront marine operations at the heart of Thai Union’s supply chain. © Will Rose / Greenpeace

We couldn’t sail by and let business as usual continue. So we’ve confronted the vessel, blacked out their lights with environmentally-friendly paint and driven them from their perch on the seamount. They didn’t like the attention and fled – we pursued and, as we write, we’re still on their tail.

And just today, at a political summit on tuna fisheries in the Indian Ocean, the use of the kind of lights on vessels like the Explorer II was banned.

It’s easy to feel small in this vast sea, but we as humans are impacting on it massive ways. It takes a movement of hundreds of thousands of people to demand change and respect for our oceans, but fortunately, that’s exactly what we have.

Tom Lowe is Multimedia Editor for the Communications Hub at Greenpeace International, aboard the Esperanza.