Six protest boats are stationed near an Anadarko drill site in the sea off the west coast of the North Island.
The boats from the Oil Free Seas Flotilla are waiting for the Noble Bob Douglas drillship, expected to arrive some time in the next couple of days.
The six boats are stationed close to the intended drill site, about 100 nautical miles off the coast.
The group's spokeswoman, Anna Horne, says at about 6am, one of the drillship's support vessels was spotted about four miles in the distance.
"It would appear it just had a little looksie...at what was going on and then sent his team back in the direction of its home port of New Plymouth.''
Greenpeace say the six boats hope to send a powerful message to Anadarko.
Energy campaigner Steve Abel says it's unclear when precisely the drillship will arrive.
"They're staking a claim to that site as a symbol of New Zealand / Oceanic territory, a symbol of a future based on clean energy not on risky fossil fuel drilling.''
Greenpeace's executive director Bunny McDiarmid and former Green Party co-leader Jeanette Fitzsimons are currently on board one of the boats.