The main terminus of the line is at Tywyn Wharf (originally known as King's Station, after a local landowner), where the railway's administrative headquarters and the Narrow Gauge Railway Museum are located. Leaving this station the line passes immediately under the A493 Machynlleth to Dolgellau road and enters a long cutting that climbs towards Pendre. From Pendre, the railway climbs up to Ty Mawr bridge and on to Hendy, the first of five minor halts, which serves the adjacent farm. More local halts follow at Fach Goch, and Cynfal, the latter having a small platform. The section from Cynfal to Rhydyronen was relaid in 1951 using rail purchased from the Corris Railway after the latter line's closure in 1948. Rhydyronen, now a request stop, was the first intermediate station built on the line, opening in 1867. Another minor halt follows at Tynllwynhen, before the passing loop and another request halt at Brynglas.
Above Brynglas, the line enters woodlands west of Dolgoch, climbing steadily, then curves to the south east and crosses the Dolgoch gorge on the Dolgoch viaduct. Dolgoch station is immediately east of the viaduct, situated on a left-hand curve at 187 ft (57 m) above sea level, and is the main intermediate station on the line, being popular with tourists visiting the nearby falls. The railway continues in a north easterly direction, passing Quarry Siding, where a halt and passing loop are located. The line continues its ascent towards Abergynolwyn station, situated on a ledge cut into the hillside. This was the original terminus of the statutory railway, beyond which the railway continued as a mineral extension, now converted for passenger use. About three quarters of the way along the 0.75 miles (1.21 km) extension is the site of the Village Incline. From here the line runs into a gorge, high above the river on a narrow ledge, ending at the foot of the first incline leading to the Bryn Eglwys quarry. Nant Gwernol station, the eastern terminus of the line, was built here on the site of a set of three sidings which originally marked the end of the original line.
This was the first intermediate station to be built on the railway, opened in 1867. It has a slate built waiting shelter and is now a request stop. A small slate quarry and manganese mine nearby once used the railway.
Request stop, once known as Tanycoed. Serves a small ballast quarry. A passing loop and ground frame is here to allow trains to pass, and a carriage shed is located here, known as the "Guest House" after a former member of the preservation society.
The original passenger terminus of the line. Most trains stop here on the return journey for refreshments, as there are no facilities at Nant Gwernol. The station has a 650 ft (198 m) long platform, capable of holding two trains.