Bat Lake is a nice singletrack 5.8 km loop trail that introduces you to basic Algonquin Park ecology while visiting a beautiful hemlock stand, a fine lookout, and acidic Bat Lake. It's easy to moderate in difficulty. The trail slowly climbs from the trailhead past a river before it reaches a beautiful lookout. The trail then slowly descends and crosses a bog before reaching Bat Lake. The lake has two small docks from which you can take in the view.
Overall, this is a nice run with some rocks and mud.