Nancy Island Historic Site is a compact but worthwhile stop near Beach Area 1. Its museum focuses on HMS Nancy, a British supply schooner from the War of 1812 whose preserved hull gives Wasaga a sharper story than the beach strip alone suggests.
It is not a big museum, so do not plan half a day around it. Pair it with a walk along the river mouth or a swim, and it becomes the useful bit of history that gives the town some depth.