It's lake Tahoe, but specifically, this area is on the western shore and it's called Emerald Bay. Not sure if you can see it, but there is a "Vikings Castle" on that little island you can see out there. A boat will take you out to the island and you can tour the old castle. I'm pretty sure real vikings didn't build it, but it's an older, authentic castle that someone built a long time ago.
Lake Tahoe is a beautiful place to visit with so much to do.