With a nearby campsite and some historical significance, Mex-i-min-e Falls is a great place to stop and spend a night or two in the swampy reaches around Watersmeet. The waterfall itself is a tad small, a minor drop over slabs of rock with a hint of froth here and there.
Heading north on 45 through Watersmeet, turn right onto old Hwy 2 (near an old mechanic's garage) and follow it for 6.5 miles. Every once in a while you catch a glimpse of Middle Branch Ontonagon running alongside this drive. Turn left onto Forest Road 4500 (which may sneak up on you) and follow it for 1.1 miles before turning off at Mex-i-min-e Falls Campsite. Park near the end of the campground and head over to the river. There are a few trails for both waterfall visitors and fishermen, so just meander upstream until you see the drop.