Black River Harbor is on Lake Superior. It's a little over an hour away from Minocqua and it is a scenic drive. There are pretty beaches at the harbor itself and lots of hiking along the river. The river had dramatic waterfalls. It's an easy hike to the various falls. After the hike, it's fun to relax on the beach. There is a small concessions/general store in the harbor. Many boats come in here from Lake Superior and even other Great Lakes.
Also nearby is Copper Peak Ski Flying Facility -- I think they still give tours. This is a one-of-a-kind facility that was out of use for some years, but is up-and-coming again. It is very dramatic -- you won't be able to believe that people willingly ski/fly off of this thing! Yikes!