I read this novel in the 1970s when I was in early-mid elementary school. The main character and her family live in a state in the upper Midwest; she’s wicked into competitive figure skating and has been training/competing for years. Because of her dad’s job (he might be a college professor), they move from a city to a more rural part of the state where there are no indoor skating facilities and no training. She checks out the lake where the other kids skate, but finds it unsatisfactory (perhaps the surface is always bumpy). She finds a perfect pond! Ice is always clear of snow and smooth. But the locals shun it. She’s happy to train there alone. Eventually, she learns the reason why the spot is shunned by locals. It was a tragedy. The family that owned the mill was holding a party there for their daughter (about the same age as the novel’s main character), there was a fire, and the girl was killed.
I read the book in grade school in the early 80's.
I remember it's a mystery book where kids visiting a lake look for a treasure. In the end, the treasure turns out to be worthless confederate money. One scene I remember vividly: The boy is tricked by the girl to swim to the bottom of the lake with his snorkel and look up. She claims it's a beautiful view. When he does so, the protective valve on the snorkel opens and water floods into his mouth.
I also seem to recall a dragon on the lake at night, but it's made of paper and burns up from the candles used to illuminate it. It is possible, however, that this memory might be from another book...
Read this in late 70s from school library, was old book. Paperback in landscape orientation, man looks for clues, crawls through tunnel under lake to island and lighthouse(?). Think it was a ghost?