The shores of Doubtful Sound in Fiordland are showing no signs of environmental damage from a large oil slick caused by a sunken tourist boat.
Up to 700 litres of diesel is believed to have spilled into the water when the Waverley sank after hitting a submerged object on Thursday night.
Eight passengers were rescued before the boat sank.
Environment Southland on-scene commander Kevin O'Sullivan says a helicopter crew and shoreline searchers scoured the coastline on Saturday but found no signs of environmental damage or distressed seabirds.
Mr O'Sullivan says wind and time have dispersed most of the original 1.7-square-kilometre slick and only about 5% of it remains.
He said boaties, tourist operators, and a float plane will provide reports about the small amount of oil.
Mr O'Sullivan said a Department of Conservation boat remained in Deep Cove over the weekend and could respond immediately if required.