Traeth Dulas is the estuary of the Afon Goch. It forms part of the sandy, shelving coastal landscape of Dulas Bay. Traeth Dulas consists of an elongated mud, sand and saltmarsh estuary, aligned north east to south west.

The estuary is approximately 1.2 miles long by 0.5 miles wide at its widest, and the reserve area covers approximately 75 hectares. It is separated from the open sea by a sand and shingle spit, with a connection to the sea through a narrow channel, approximately 50m wide. Traeth Dulas is bounded by a steeply rising limestone escarpment on the south side, and by more gently rising agricultural and park land to the north.

The Afon Goch rises partly from Mynydd Parys, and as a result is polluted by metals from the old mine workings. The flat expanse of the estuary contrasts with the steeply rising wooded escarpment on the south side and Mynydd Bodafon in the near distance to the west. On the north side the land rises more gradually towards Mynydd Eilian. The whole forms a highly attractive landscape, with beautiful coastal scenery, wide, sandy beaches and panoramic views eastward to the Great Orme headland and beyond.

It is possible to park at the western end of the estuary, but be aware, the whole area becomes inundated at high tide, so it is worth checking the local tide times before you visit to avoid getting cut off.