Did you know boats can "sail" underwater? Submarines use a principle called "hydrodynamic lift," akin to a boat's sail, to glide beneath the waves. Their fins act like wings, providing lift as they move, allowing them to maneuver with grace despite their bulk. This fusion of maritime and aeronautic engineering showcases the versatility of watercraft. Share your own fascinating fact about boats or watercraft – you might just reveal another hidden gem of the nautical world!