One of my favourite places is Semerwater, a natural glacial lake in Raydale (which is a dale on the south side of Wensleydale, North Yorkshire). I have enjoyed walks in Raydale and evening picnics next to the shore.
I remember learning a song at primary school based on the legend about Semerwater, where a beggar visits a thriving city and visits houses asking for food and drink, but is turned away until he reaches a small cottage where he is given food and shelter. The next morning he curses the city with these words: “Semerwater rise Semerwater sink and bury the town all save the house where they gave me meat and drink.”
On the most recent walk around Semerwater I came across the ruins of the original church of St Matthews, Stalling Busk. It lies about 400m north of Stalling Busk and was in use until the early 20th century. (OS grid ref: SD916863)
The Lake Semerwater website gives some information about walks, and the Car Free Walks website includes a walk from Bainbridge round Semerwater and back along the old Roman Road. It is a beautiful walk (be warned though – there is plenty of height to climb).
There is a Yorkshire Wildlife Trust nature reserve at Semerwater, more details on their website.
There is more information about the lake, including parking details, on the Lake Semerwater website.