Air passage and Schnorkel

Air passage noun - A duct that provides ventilation (as in mines).

Schnorkel and air passage are semantically related. In some cases you can replace term "Schnorkel" with "Air passage", this terms are similar.

Schnorkel noun - Air passage provided by a retractable device containing intake and exhaust pipes; permits a submarine to stay submerged for extended periods of time.

Air passage and schnorkel are semantically related. You can use "Air passage" instead a noun "Schnorkel".