Castalia Ohio is known for its "Cold Creek" rising up from a spring, the water temperature barely changes and it never freezes. The tourist site "Blue Hole" is no longer open, but this small town's fish hatchery is famed for its trout, stocked since the mid 1800's, which adapt well to the cold water stream.
Just north of the junction of Rts 6 and 269 in Sandusky, the cold creek empties into the Sandusky Bay. This area provide excellent fishing for a wintering population of Bald Eagles.
one can find the most amazing assemblage of winter Black-crowned Night-herons I have seen gathered in Ohio. This would make a wonderful photographic opportunity as the birds are as close as I have ever seen them. The BCNH are spectacular looking birds, and always a thrill for me.
On to Castalia! The center of town features this large pond, a regular "spa" for wintering ducks and geese. You can see the warmth (probably a balmy 47 degrees...) provided by the underground springs.
The ducks and geese like it just fine, and enjoy basking in the open water when all the surrounding streams and ponds are frozen over.