Greenpeace executive director Russel Norman and climate activist Sara Howell will plead guilty to trying to obstruct an oil industry survey ship.
Former Green Party co-leader Norman and Howell swam in front of the Amazon Warrior as it searched for oil off the Wairarapa coast in April last year.
Greenpeace said today the pair would "plead guilty and seek a discharge without conviction, on the basis that their conduct was justified and necessary to bring about required change to government policy".
Norman said they would also make a plea for mitigation.
"On the grounds that our actions were reasonable and honourable given the threat of climate change, we remain hopeful that the Court will agree, given the importance of this issue," Norman said.