A couple of years ago, two buddies and I backpacked up to Half Dome in Yosemite. It's not a big hike, but getting reservations is the really hard part.
After coming down from the peak, we started to set up for dinner. Each campsite is spaced out a little, but still in view of each other.
Everyone was back except for a couple who was still on the trail.
Three black bears just walked right through the campsite, past all of us like we weren't there, and went to the backpacks of that couple. They tore open their packs so fast, nobody reacted. Then we all started making noise, banging pots and throwing rocks at the bears to scare them off.
They were only about 20 yards from my campsite.
Reluctantly, they moved away, but not too far. That entire night, those bears would circle around the campsites, and we'd all end up making noise to scare them off. It was a very long night!
I did manage to get some sleep, but when I woke up, one of the bears had left his deposit about ten feet from my sleeping bag.