Seathwaite is a village in the Duddon Valley, Lake District, England. The place is located in the civil parish Dunnersdale with Seathwaite. The Tarn Beck, which has its origin in the Seathwaite Tarn north-east of the town, flows past Seathwaite and flows west of the settlement in the River Duddon. William Wordsworth is said to have stayed more often at the local inn. He dedicated the poem XVIII to his Duddon Sonnette to the place and the Reverend Robert Walker. Walker lived in Seathwaite for 66 years and was known as the Wonderful Walker. The Holy Trinity Church in Seathwaite, home to a memorial to Walker and his wife, was completely rebuilt in 1874 and is now a Grade II protected monument.