Y Felinheli, formerly known in English as Port Dinorwic, is a village and community beside the Menai Strait between Bangor and Caernarfon in Gwynedd, northwest Wales. Etymologically, its name comes from the Welsh y meaning the, melin meaning mill and heli, meaning brine/salt-water/sea. An alternative interpretation is from Y Felin Heulyn, "the m…Y Felinheli, formerly known in English as Port Dinorwic, is a village and community beside the Menai Strait between Bangor and Caernarfon in Gwynedd, northwest Wales. Etymologically, its name comes from the Welsh y meaning the, melin meaning mill and heli, meaning brine/salt-water/sea. An alternative interpretation is from Y Felin Heulyn, "the mill on the River Heulyn", which refers to the river that runs into the village.