An interesting diversion from the Duddon. A hard slide/slot at the put-in leads into a continuous gorge section and a final rocky fall, before levelling out as the beck joins the main river. A good giggle.
As you drive through Seathwaite up the valley you'll see Tarn beck on your left. Park up next to the stone wall and put on as high as the water level/value of your boat allows. Take out after the final fall by the footbridge, or combine with a run of the lower Duddon.
Rainchasers is best experienced as an app.