FIRST-HAND; Greenpeace activist Jon Castle on saving the planet
WHEN I FIRST became involved in Greenpeace in 1978, aged 25, I had always worked at sea and, being committed to justice, the whaling issue made sense to me because there's no justice in driving a species to extinction. I joined the Rainbow Warrior ship in Iceland on the first whaling campaign with a brilliant crew: a collection of odd-bods with a sense of purpose, far better than a regimented army of yes-men.

We went about 110 miles out into the North Atlantic, a pretty scary place to be with the menacing sight of the whaler ships' distinctive profile: a raised prow with a huge gun at the top and a tall red and black funnel. But it was a sensational experience, the whalers didn't know what was going on. No one had ever come over the horizon before in a green boat painted with bright rainbows to put little boats in between them and the whales.

It was hard going because the sea was rough and the Icelandics kept driving their ships into the wind to tire us out. We were facing the waves in our tiny boats with me steering, having to look both ways so that we were constantly in front of the guns and behind the whales. Our tactic as non- violent protesters was to lay the situation on the conscience of the adversary so that they would ask why the hell these people were risking their lives for a whale and whether it was worth hurting us to get it.

When you're at a distance you think with your head, but in the spray with the whale gliding out of the water next to you, you think with your heart, so it's not difficult to put your life on the line. Occasionally we would lose a whale after many hours of protecting it and that would be very emotional. They often took a long time to die, flippers just flapping a little and blood pumping out into the sea. It left a very strong and lasting impression.

From Iceland we went to stop the British from dumping nuclear waste. We'd put our boats underneath the ramps so that the waste couldn't be rolled into the sea from their ships. Since they were squirting water hoses at us we couldn't see anything and the suspense of knowing that there were barrels filled with concrete balancing just a few feet above our heads was perhaps more frightening than the whaling. Then we went to stop the Spanish whalers. The first occasion wasn't too bad but in 1980 I was arrested with the ship for five months. Half the engine was taken away but the engineer went back to England and reproduced the missing part, which we secretly put into place. Then we made our escape, slipping out of the port one night. Although they sent three warships and aeroplanes after us they couldn't find us.

After that I protested against nuclear testing, the transport of nuclear waste and the dumping of sewage and chemical waste into the sea. There were plenty of times when I got covered in shit or chemical waste as I tried to clamp covers on to the sewage pipes. Other protesters experienced worse contamination; one of our female protesters got contaminated with radiation and had a genetically damaged baby. You can't prove the connection but . . .

I stopped working for Greenpeace in 1990 but earlier this year I agreed to join the protest against the proposed dumping of Shell's Brent Spar oil storage unit. Our objective was that once on the platform we weren't going to get off it, the message was simple. We blocked the main access to the platform and then as the barge arrived the other protesters rushed out to try to stop the men from landing in a crane basket as I went to hide deep down in the structure.

It was a strange place, like descending into another realm or an abandoned spaceship. I locked myself in behind steel doors which took 10 hours to break down. What deeply touched me as I was taken on board the barge was the deck hands discreetly shaking my hand.

The only problem now is that the court has given me seven days in which to reveal to Shell the names of everybody who has been involved in any way in the occupation of the Brent Spar platform, which I won't do. But I'm glad to say that as a result of our action the EU commissioner for the environment and the European Parliament are supporting Greenpeace in opposing the dumping.

After the sabotage of the Rainbow Warrior we coined the phrase "you can't sink a rainbow''.

Interview by Katie Sampson