We're on our way to identify yet another bottom trawler, which is bottom fishing in international waters. We've documented several already today, with two of our inflatables racing all over the sea, photographing and filming the trawlers as they drag up their catch from a kilometre below.

This morning, four of us were in the Waka Nui inflatable, tracking one ship, registered in Nelson, New Zealand. After it hauled up a relatively small catch of fish, we trailed it for a bit. When it dropped its nets again, we found a bunch of albatrosses squabbling over some of the bycatch. Armed with a landing net, Kat managed to grab two small sharks, with their intestines hanging out.

Later in the day, both inflatables shadowed a ship called the Chang Xing, registered in Belize. We photographed and filmed it pulling up a net of orange roughy. We then gently pushed through a thousand-strong flotilla of huge hungry albatrosses, while roughy heads were spat out a hole in the side of the trawler. Kat, Anna and I were out on the bow of the boat, netting any interesting bycatch that we could grab before the birds, while Francisco and Roscoe navigated us through. Sarah was on the wheel of the Avon inflatable, with Wooly and Roger festooned with camera gear.

Once a bottom trawler starts hauling up its catch, it can take 20 minutes or more to reach the surface. First, the huge (1-6 tonne) metal doors, which act as sort of wings to keep the net open, come out the water, and bang up against the side of the ship. As the net floats on the surface, most of the fish are already dead, organs ruptured from the sudden depressurisation - the 'bends'.

Then there's the hundreds and hundreds of disembodied orange roughy heads bobbing about on the surface, with their doleful eyes being pecked out by an albatross. Orange roughys have a very slow body clock. The live for up to 150 years in the deep sea, and don't breed until they're 20 or 30 years old. It's a shame to see bits of these ancient fish scattered around the sea, while the rest of their bodies are shipped off around the world.

But back to our night mission. After dinner, it's back into the boat again and off into the dark. As we approach our target vessel, we get our gear out of the waterpoof case. Derek is armed with a stills camera, and I've got a digital video camera, switched to infra-red. We sidle up alongside the lit-up bottom trawler, which has its nets down. This is a pretty small boat - maybe 30 metres long. We're looking for identification... up along to the bows, and there it is, the name and number. We get photos and footage, then stow the electronic gear, before bouncing back across the lazy waves to the Rainbow Warrior, with just a brief stop to take in the infinite sky above us.

Photos from our mission can be downloaded at www.greenpeace.org.nz/photos/09June04/