Lying at a height of 664 feet, it covers an area of 22 acres (89,000 m2), and is long and narrow in shape.

A natural lake, the building of a dam at the southern end raised the level to provide water to drive machinery at the nearby Aberllyn lead and zinc mine, which in 1900 employed some 200 men.

The outflow of the lake today passes the ruined remains of the mills before joining the River Conwy.

Some sources quote that the area around Llyn Parc is reported to be one of the few remaining strongholds of the red squirrel.

This is not so, confusion having arisen between this location and the similarly named "Llyn Parc Mawr" at Newborough on Anglesey.