An Bord Pleanála has approved planning permission for the final section of the Corrib gas pipeline in north Mayo.
It is the third application made by Shell E&P Ireland in over a decade.
The revised new route will include an undersea tunnel going through Sruwaddacon Bay, which will carry a 5km section of the pipeline.
The tunnelling is a safety measure following concerns about the proximity of the previously proposed routes to residential areas.
The new route will link the pipeline landfall at Glengad to the €1bn gas terminal at Bellanaboy.
The Corrib Gas Project has been mired in controversy since the gas field was discovered off the Mayo coast in 1996.
Local people have been opposed to the pipeline on health and safety grounds and environmental campaigners have staged numerous protests over the past 15 years.
Shell Ireland has always insisted that the building of the pipeline was to the highest international standards and posed no threat to people living in the area or to the natural environment.
Once in production, the Corrib gas will be distributed to homes and businesses throughout Ireland within three years.