GoWaterfalling says that Agate Falls is an impressive waterfall that’s relatively easy to get to:
Agate Falls is a Michigan State Scenic Site 6.5 miles east of Bruce Crossing on MI-28. There is a roadside park (Joseph F. Oravec roadside park) just past the bridge over the Ontonagon River. This is one of the largest and most impressive waterfalls in Michigan. Unfortunately the provided trails and overlooks are somewhat limited. With some effort you can scramble down to the river to get some very good views of the falls, which seems to be popular with local fishermen, or scramble up the river banks to get to the old railroad bridge over the falls. The bridge is now part of a snowmobile trail.
More Michigan waterfalls on Michigan in Pictures!