Leonardo da Vinci designed a diving suit as an underwater breathing apparatus with two breathing tubes connected to a mask.
Leonardo described the equipment in notes associated with his studies of underwater exploration. The design included a mask, breathing tubes, and a float or supporting structure intended to keep the tubes above the water. Some accounts also describe a bag for collecting urine, reflecting the practical problems of remaining underwater.
The design was not a modern scuba system. Leonardo did not have compressed-air cylinders, and his proposed tubes would have been difficult to use safely because water pressure and tube length limit how a person can breathe from the surface. The concept is therefore best understood as an inventive Renaissance diving proposal rather than a successfully tested apparatus.
People sometimes call it a submarine, but it was personal diving equipment, not a vessel. Leonardo’s notes show interest in naval engineering, underwater movement, and military technology, although there is no firm evidence that the suit was built or tested.