A famous feature is a naturally formed pool known as the Devil's Pool, near the edge of the falls, accessed via Livingstone Island. When the river flow is at a safe level, usually during the months of September and December, people can swim as close as possible to the edge of the falls within the pool without continuing over the edge and falling into the gorge; this is possible due to a natural rock wall just below the water and at the very edge of the falls that stops their progress despite the current.