Snorkel Retractable pipes fitted to later U-boats that brought air into the engines, and let exhaust out, allowing the boats to run on diesels while submerged.

• 通气管,潜艇上部装置的可收放管,用于向柴油发动机输送空气并排出废气,是潜艇能在潜航状态下使用柴油动力。