We stayed here for a church group camping event.  Clean bathrooms, great sites.  Lots of room for kids to run around.  Close to the beach and a great local brewery.

Accessible via hiking or (rented) boat.  This campground has beautiful locations for reading, hiking, and canyoning.  Bear boxes provided and a well-maintained pit toilet.

My first time camping at Ross Lake was at Colonial Creek - which actually has access to Diablo Lake.  It was pouring down rain - typical for the Pacific Northwest, but we still had a blast.  Clean bathrooms, plenty of space for cooking, cleaning, playing card games.

We do an annual hiking trip at Ross Lake.  Amazing hikes, glacier-fed lake - which is icy cold if you decide to hike all the way up to Desolation Outlook and need to cool down your body after the evaluation climb.  You can rent motorized boats to access even more campgrounds.  Canoe or stand up paddleboard.  There are always rangers refilling toilet paper and checking on the conditions of the pit toilets which I always appreciate and bear boxes to keep your food safe.