A submarine periscope allows a submarine to observe what?

• A. From inside the hull using infrared.
• B. Underwater imaging via sonar.
• C. Only during surfaced operations.
• D. Above the water while remaining submerged.

Answer: (D)

A submarine’s periscope lets you see above the water while the boat stays submerged. Light from above the surface is funneled through a tube with mirrors and lenses, so the crew can view surface features from inside the hull without exposing the submarine. This preserves stealth and safety. Infrared imaging isn’t how a standard periscope works, and sonar provides underwater, not visual, imaging. You don’t have to surface to observe; you can observe above the water while still submerged.