Brown bears (Ursus arctos) are the only bears to regularly inhabit Katmai National Park and Preserve. In 2005 there was one verified sighting of a black bear (Ursus americanus) in Katmai. This is the only verified sighting of a black bear in Katmai’s history. Black bears are more commonly found north of the park boundaries in Lake Clark National Park and Preserve. Yes. The bridge over the Brooks River is a floating bridge and bears can swim between the pontoons that keep the bridge floating. Not all bears choose to swim under the bridge. Every year, there are bears that seem to prefer walking around the bridge instead of underneath it, but most bears that frequently fish near the bridge will swim underneath it.