Porthmadog is a compact coastal town in Gwynedd, northwest Wales, sitting at the mouth of the Afon Glaslyn and alongside the large reclaimed salt marsh of Traeth Mawr. It grew up in the early 19th century after William Madocks built the Cob to create a harbour and reclaim land, and prospered as the slate-exporting port for nearby quarries around Blaenau Ffestiniog.
Today Porthmadog mixes maritime and tourist economies - a busy marina, boat trips and a working quay sit beside cafes and holiday accommodation - and it’s a gateway for walkers and climbers heading into Snowdonia. The preserved narrow‑gauge Ffestiniog Railway remains a cultural and historic draw, the estuary is important for birdlife and conservation, and the town still has a strong Welsh‑speaking community with a lively seasonal atmosphere.