Divers have located the fishing vessel Ayson which sank off Stirling Point near Bluff.
The boat hit rocks carrying an estimated 3000 to 5000 litres of diesel hit rocks early on Friday morning.
Three crewmen were rescued from a life raft by the Southland Coastguard and were not injured.
The 13.4m trawler was found 700 metres south of Stirling Point on Saturday and divers have sealed breather pipes on its fuel tanks.
Dallas Bradley of Southland Regional Council said very small amounts of diesel may still be leaking from the vessel.
A dive team and equipment was being organised to salvage the vessel early next week.