A whirlpool is a body of rotating water produced by opposing currents or a current running into an obstacle. They can occur in oceans, rivers, and lakes, often forming when water flows over underwater features like rocks or when two currents collide. The rotation can create a funnel shape, drawing objects and water into its center. Whirlpools can vary in size and strength, with some being small and harmless, while others can be large and dangerous. Famous examples include the Maelstrom in Norway and the Narrows in the Strait of Messina. Safety precautions are essential when near these natural phenomena.