Leopard seals are dangerous apex predators found in the Arctic Circle. They can weigh between 400 and 1300 pounds, and swim at speeds of up to 18 mph. Due to their aggressive nature, divers are advised to stay at least 100 feet away from them. While they generally do not attack humans, there have been rare incidents, including one where a researcher was attacked. Being aware of their behavior and keeping a safe distance is crucial for scuba divers in their habitat.