The A498 descends from a 277 m (909 ft.) summit at Pen-y-Gwryd and runs south west through the village of Beddgelert and the Aberglaslyn Pass, where it overlaps the A4085.

There is a steep descent of Nantgwynant and some 1+3⁄4 miles of this is on a substandard, narrow twisting alignment, where larger vehicles have difficulty in passing.

The road passes through Beddgelert by way of a sharp right angled bend over a river bridge, not recommended for articulated vehicles.

In the Aberglaslyn Pass the trackbed of the Welsh Highland Railway, now being reconstructed, can be seen on the opposite side of the Afon Glaslyn.

Unfortunately the bridge was rebuilt with such narrow dimensions that vehicles wider than a standard car find it difficult to pass.