We always found Presqu’il to be a wonderful park for our kids , they not only have accessible trails , campsites, and beaches but fabulous programs for the little ones.
We recently visited Lake St Peter, right up on the south east tip of Algonquin park and it was beautiful! Our kids, 3 and 1 had a great time! Two beaches, one very close to our camp ground which was small and sandy but perfect! They had so much fun they cried when we had to pack up and go home!
Also, if you’re coming from the western side of Algonquin park, the drive is breathtaking!!! Our GPS took us on this small road that drove parallel to the southern tip of Algonquin park. You will not believe the beauty, the thickness and the pure silence that you will meet on that road. That alone was worth the trip.