The snippets do not describe a POI located on Afon Heulyn — Port Dinorwic Marina sits on the Menai Strait, not on that river.

However, the POI name and location match the marina described in the snippets closely enough to provide an accurate description based on available information.

Port Dinorwic Marina is a Grade II listed marina situated on the Menai Strait in Y Felinheli (Port Dinorwic), North Wales, roughly midway between Bangor and Caernarfon.

The marina occupies a locked, tree-lined creek off the Strait and offers year-round cruising in sheltered waters. Access through the lock is available approximately three hours either side of high water.

The surrounding area is largely residential, with a handful of cafés and restaurants near the marina gate and shops along the top road toward the harbour.

Several boatyards and marine services businesses, including dedicated marine engineering firms, operate nearby.

The Menai Strait itself serves as a useful shortcut between West Wales and Liverpool, and the marina makes a natural stopping point for passage-makers navigating its strong tidal streams.