The coastguard is continuing to monitor an area around 25 miles off Mizen Head on the south-west coast after the sinking on Monday of the Spanish-crewed fishing vessel, the Ixkote.
Twelve crew members were rescued shortly after 11 a.m. when their boat sprang a leak in the engine room and began taking in water. One crew member was treated for slight injuries to his arm.
The British-registered 200-tonne vessel had left Castletownbere, Co Cork, that morning and had reached the fishing grounds when the leak sprang suddenly. It had around 20,000 litres of diesel as well as around 200 litres of lubricant oil.
According to local fishermen, the speed of the sinking was surprising. Another flag of convenience ship, a French-registered, Spanish-crewed fishing vessel, was alongside at the time and was able to rescue the crew members.
"It was only a matter of two to three hours between leaving Castletownbere and sinking," one local said.
The Ixkote, in common with many of the Spanish-registered vessels in the area, was up to 30 years old. It was fortunate it was daylight when the vessel began to sink, locals said.
A spokesman for the Valentia coastguard said the coastguard helicopter had checked for pollution and had noticed just a small sheen near the sunken vessel.