Tauranga is leading New Zealand's Earth Hour celebrations this year, recognising the community's response to the Rena disaster, organisers say.
A night market and candlelit acoustic concert for families and other residents will lead up to the lights-out hour from 8.30pm on Saturday, part of a worldwide dimming of the lights.
The city's experience with the nearly six-month-old Rena disaster - New Zealand's worst maritime environmental disaster - had provided a strong reminder of the importance of our natural environment and also inspired such a positive community response to assist with the clean up, Tauranga City Council said.
Landmarks switching off include Auckland's Sky Tower, Wellington's Parliament Building, the Sydney Opera House, Sydney Harbour Bridge, Tokyo Tower, the Eiffel Tower and the Great Wall of China among hundreds of others.
This year a record 150 countries and territories, including Libya and the International Space Station, will turn off the lights for one hour on Saturday night as the world marks Earth Hour.
The last country to usually go dark, Samoa has crossed the International Date Line and this year will kick off the lights off event an hour before New Zealand.
The last switch-off event will wrap up in the Cook Islands.
The movement, a mass symbolic gesture supporting environmental action, began in Australia five years ago and has grown to include 6000 cities and some of the world's most famous landmarks.
Corporations around the world will also turn off their lights and millions of households are expected to take part by switching off lights and appliances.
Libya's Martyrs' Square, a focal point for the 2011 revolution, will join Earth Hour for the first time.
Parts of Iraq and Afghanistan will also take part and Dutch astronaut Andre Kuipers will turn off lights on the International Space Station.