How do submarines use periscopes?

Submarines use periscopes to enable crew members to observe the surface of the water while remaining submerged. A periscope consists of a long tube with mirrors or prisms that allow light to enter from the surface and be redirected to the viewer’s eye. This allows for a 360-degree view of the surroundings, helping submarines to navigate, spot other vessels, and assess threats without exposing themselves. Modern submarines may also use advanced optical or electronic systems for enhanced surveillance capabilities.