Walk for the Planet, which began yesterday, includes hundreds of church members and community groups walking 945km in relays from Stewart Island to Wellington, planting trees along the way.
It has been timed for the 40 days of Lent, the period of prayer and self-denial which many Christians observe in the lead-up to Easter, and will culminate with a combined church service on Easter Sunday, April 12.
The concept was first raised at the Methodist Church national synod held in Queenstown last year, University of Otago chaplain Greg Hughson, who is helping to organise the Balclutha to Oamaru legs, said this week.
This was the first time churches had campaigned collectively for the environment, and was the first large-scale co-operative venture since the Hikoi of Hope in 1998, which highlighted poverty.
"This is a very important and historic event . . . It is a chance for people to slow down and listen to the rhythm of the earth, and hopefully it will stimulate ongoing action from churches and others to think about what is happening to the earth and [get] people to change their ways."
Up to 300 people were expected to walk from the outskirts of Dunedin to the Octagon on March 7, where they would be met by Mayor Peter Chin, Mr Hughson said.
The following day - one of seven rest days on the walk - a combined church service would be held at 5pm in the grounds of First Church, Moray Pl.
Walkers would leave the city on Monday, March 9, heading for Waitati via the Orokonui ecosanctuary.
The denominations involved in the Otago legs were Methodist, Presbyterian, Salvation Army, Anglican, Quaker, Catholic and Baptist, along with the Students for Environmental Action group and Sustainable Dunedin, he said.
Some members of the Jewish and Muslim faiths would also participate, something Mr Hughson did not see as incongruous.
"We can all affirm a common belief in God as the creator of the earth. We all have a huge responsibility as stewards of creation."
