I'm listening to an audiobook about Irish history (A Brief History of the Druids) and was surprised to learn that in the Iron Age, Celts would make offerings to the gods by throwing their swords (and other metal items) into lakes and rivers.
I immediately thought of the Lady of the Lake tale from Arthurian legends, and lo and behold, I'm not the only one. Check out this webpage that describes the ritual in more detail and connects the Lady of the Lake to Celtic water goddess mythology. Celtic Iron Age Sword Deposits and Arthur's Lady of the Lake
Cool stuff! I wish my English classes in college had brought in more history.
Mignon Fogarty is better known online as Grammar Girl