Greenpeace says beach demonstrations around the South Island on Saturday are a clear message New Zealanders don't want offshore drilling.
The Texan company Anadarko is about to begin drilling its first test well off the Otago-Southland coast in the search for a possible gasfield.
Greenpeace says more than 2000 people gathered on 21 South Island beaches in protest on Saturday afternoon.
Energy campaigner Steve Abel says protesters, including families, fishermen, tourism operators and iwi representatives, demonstrated they want a clean energy future for New Zealand.
He says the biggest turnouts were at beaches in Dunedin, with 600 people, Christchurch, with 500, and Kaikoura, 350.
Mr Abel says this shows people are very much saying they don't want dozens of oil rigs dotted around the coastline.
He says they want jobs for New Zealand that don't risk ruining fishing grounds or leave oil washing up on beaches.