This one's a little ways away from the Keweenaw, but worth the trip, especially if lined up with Bond and O-Kun-De-Kun Falls and the Friday night crab buffet in Watersmeet. Situated on the Middle Branch of the Ontonagon River, downstream from Bond Falls, Agate Falls is an impressive sight, especially when viewed from the bottom of the gorge it feeds into. Park your car at the Agate Falls roadside park (vault toilets here if needed). There's a decked pathway that leads underneath the road and the railroad bridges that span the river and ends at a deck that looks over the falls. If you get off of this pathways about when you walk under the train bridge, you can follow some footpaths down the gorge and to the bottom of the falls. In my opinion this view is much more impressive. Just be careful as the slope is very steep and on wet days it is very easy to loose your footing.
To get here from Houghton, head west through the yooper loop and onto M-26. Drive for ~38 miles and turn left onto M-26 (if you go straight the road transitions to M-38). Continue for 5.5 miles and turn left onto US-45. Continue 14 miles to Bruce Crossing and turn left onto M-28. In 6.8 miles you will see Agate Falls roadside park on your right. Park here.