The two bears mate midstream. The scar across the male's back is from some skirmish with another male, probably over a fishing spot.
Aerial view of the entire Brooks River, with the falls in the middle and Brooks Lodge at the far left. To get to the falls, we had to walk about a mile, crossing the river on the bridge near its mouth, and then follow a trail through the woods on the far side of the river. You can't see that trail, but you can see the elevated walkway at the end of the trail leading up to the falls; the walkway keeps visitors above/away from big bears that are taking breaks from fishing - or carrying their fish into the woods to consume.
A better look at the three locations that have observation platforms, from which visitors can observe and photograph bears safely: 1) the Falls, 2) the "Riffles" just above (downstream from) the Falls, and 3) the bridge across the river just before its mouth at the top. You can also see the Brooks Lodge at the top left.