On Friday, Geraldton man Glen Pendlebury climbed up a tree in Bentley to protest against the City of Canning's plans to cut down more than 100 eucalypts.
That effort saw him and other environmentalists issued with a move-on notice by police.
But Mr Pendlebury has now landed himself in a much more serious and dangerous situation - as a prisoner aboard Japanese security ship the Shonan Maru 2, which is supporting the Japanese whaling fleet. He was one of three members of environmental group Forest Rescue Australia that managed to sneak aboard the vessel yesterday.
Mr Pendlebury, 27, has a history of radical environmental activism and was working for Greenpeace until recently. His mother Linda Saunders said yesterday she was desperate to know whether her son was safe and unharmed.
Ms Saunders said she did not always agree with the way he pursued his causes, but respected his passion for environmental issues.
"Glen is very passionate about what he is doing but I would like him home safe and sound as soon as possible," she said.
"I don't think he really understands the predicament he is in."
Ms Saunders said she had been assured by Foreign Affairs Minister Kevin Rudd's office that the Government was doing everything it could to help her son.
"I just feel he got caught up in this and I want him home," she said.