| Pen Pumlumon Arwystli | |
| Elevation M: | 741 |
| Prominence M: | 64 |
| Parent Peak: | Pen Pumlumon Fawr |
| Listing: | Hewitt, Nuttall |
| Language: | Welsh |
| Location: | Ceredigion, Wales |
| Range: | Cambrian Mountains |
| Coordinates: | 52.475°N -3.7458°W |
| Grid Ref Uk: | SN789869 |
| Topo: | OS Landranger 135 |
Pen Pumlumon Arwystli is the second highest summit on the Plynlimon massif, a part of the Cambrian Mountains in the county of Ceredigion, Wales.
The summit is grassy, and is marked by 3 large ancient cairns. The views include Rhos Fawr, Drygarn Fawr, Pen y Garn to the south and Aran Fawddwy, Glasgwm, Tarrenhendre and Tarren y Gesail to the north.
The longest river in Britain, the River Severn, has its source on a lower boggy plateau to the north of the summit.[1]