It will be a workout for kids, but it's accessible if they like hiking.
Yes, fine for kids. Our kids 14, 10, 6 all had a blast. We went clockwise on Lumpy Ridge then up to Gem Lake. Gem Lake has serious vert gain with lots of tall stone steps along the way. If your kids haven't done much hiking you might cut out the Gem Lake hike - but it's marvelous up there.
We saw several kids about 2 yo and up. The 6 yo was crying. Mine probably would have too. But I promise gem lake is worth the uphill hike for you and the kids. Lumpy ridge was not much elevation gain if you go up the right entrance. Great views. Rangers will be there to help with any questions.
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