Tom Ghyll which drains beautiful Tarn Hows, can be accessed from the tarn's dam. It flows through wooded Glen Mary, who had its name bestowed upon it by the Victorian poet, artist, critic and conservationalist John Ruskin, who felt Tom Ghyll needed a more picturesque name.
The Ghyll descends through a series of waterfalls down the scenic valley to Glen Mary bridge. Glen Mary is a popular spot for walks. A right turn and a short walk down the adjoining road brings the walker to Yew Tree Tarn, a small and picturesque lake.