On watch in the Forest of Dean, Harry sees a silvery doe and follows it to discover Gryffindor’s sword in a frozen lake; when he tries to get it, Ron appears, saves Harry’s life when the locket tries to strangle him it the water, and uses the sword to destroy the locket Horcrux.
Harry later discovers that the doe was Snape’s patronus; he had placed the sword at the bottom of the lake, and was leading Harry to it.
Harry saved Ron from a lake during the second task of the Triwizard Tournament (GF26). -BB
In Arthurian legend, some accounts say that King Arthur received the sword Excalibur from the Lady of the Lake. (source: Wikipedia) -BB
Christian symbolism in the chapter "The Silver Doe" has been the subject of much conjecture, with many equating the silver doe with Christ and concluding that Harry's submergence represents baptism. (sources: How Harry Cast His Spell by John Granger, The Gospel According to Harry Potter by Connie Neal) -BB
From the Web
Official website on the Forest of Dean region: http://www.wyedeantourism.co.uk/