Traeth Mawr

A large embankment, called the Cob, separates the area from the sea and carries a road and railway line.

The original estuary of the Afon Glaslyn was a dangerous place; many people were said to have died in the quicksands trying to cross the Traeth Mawr.

Soon afterwards he reclaimed an area of sand from the sea and the river by building a 2 mi (3.2 km) earthen bank from Prenteg to Clog-y-Berth (now Porthmadog).

[2] Between 1808 and 1811 an embankment called the Cob was constructed from the island of Ynys Towyn (now part of Porthmadog) to Boston Lodge in the Meirionnydd.

Until September 2003, when the Cob was bought by the Welsh Assembly Government, all vehicles crossing the embankment were required to pay a toll.

The collection of fees often caused traffic jams at peak holiday travel times: it was not exceptional for queues to back up to one mile (1.6 km) in each direction.

In 2012, 260 m (850 ft) of the embankment were widened on the seaward side of the Porthmadog end to allow a second platform to be constructed at the Ffestiniog & Welsh Highland Railway's Harbour Station.