What is the function of a submarine periscope?

• A. To perform sonar calibration.
• B. To launch torpedoes while submerged.
• C. Visual observation while remaining submerged below the surface.
• D. To communicate with surface ships via radio.

Answer: (C)

Visual observation from underwater is the function of a submarine periscope. The periscope is an optical system that lets the crew look over the surface while the hull stays mostly below, keeping the submarine hidden. When at periscope depth, a small portion of the mast rises above the water to bring a view of the sky and surface into the tube, while the main body stays submerged for stealth. This lets the crew identify ships, land features, weather, and navigational cues, and take bearings without surfacing. It isn’t used to launch weapons, calibrate sonar, or communicate via radio—the periscope’s purpose is strictly to provide a visual, line-of-sight view above the water.