Port Dinorwic is situated on the stretch of water between the Isle of Anglesey and the Welsh mainland known as the Menai Straits. It is just five miles from the Cities of Bangor and Caernarfon in North Wales.

The name 'Port Dinorwic' no longer appears on Maps, it is now known by its Welsh name Y-Felinheli. The dock itself is also known as 'Menai Marina' or the' Vaynol Dock'