An application to expand Galway Harbour has been lodged with An Bord Pleanála.
The proposed development, which has been planned for many years, would cost €126m.
It is hoped the project would be completed by the end of 2017.
The Galway Harbour Company said 200 jobs would be created during construction and up to 800 jobs could eventually result, due to increased activity at the port.
The company's chief executive Eamon Bradshaw said expansion is vital for the economic advancement of the western region.
A decision from An Bord Pleanála is due in about six months.