The Devil's Pool, a small lagoon, enclosed by rocks, on the edge of Victoria Falls overlooking a 100m gorge...
A famous feature is a naturally formed pool known as the Devil's
Swimming 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.
Here is a video of devil's pool....