The school serves the towns of Porthmadog, Cricieth and the rural villages of the area.
One of its most famous ex-students was the poet and scholar T. H. Parry-Williams, who first attended the school aged 11 in 1898.
Rob Piercy, a successful local artist, was previously the art teacher at Ysgol Eifionydd.
According to the latest Estyn inspection report conducted in 2018, 69% of pupils come from Welsh-speaking homes.
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