The Sleeping Bear Dunes National Lakeshore’s North Bar Lake page says:
North Bar Lake is one of the most popular beaches in the Lakeshore because it has shallow, clear water over a sandy bottom makes for warmer swim than in Lake Michigan. But for those who like the refreshing cool water and wave action of the big lake, you can walk across the low dunes that separate the two lakes in just a couple of minutes. The beaches of pure sand and the small outlet to Lake Michigan is ideal for the kids to play.
Take a hike over the dune that separates North Bar Lake from Lake Michigan. On both sides of the trail you will see plants native to the dunes: Dune grass, pitcher’s thistle, wormwood, sand cress, and others. These plants help stabilize the dune. Once at the Lake Michigan beach, you can walk along the shore north to the bluffs below the Pierce Stocking Drive Lake Michigan Overlook Platform. This perspective gives you a better appreciation of the size and steepness of the bluffs.
You can get to North Bar Lake by taking LaCore Street north out of Empire to Voice road and then Bar Lake road. There is a large parking lot with restrooms which can be used for changing. Also, if you forgot to buy your Lakeshore Pass, you can use the Self-Service Envelope system right there at North Bar Lake.