Air passage and Snorkel breather

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

Snorkel breather and air passage are semantically related. In some cases you can replace phrase "Snorkel breather" with "Air passage", this phrases are similar.

Snorkel breather 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 snorkel breather are semantically related. You can use "Air passage" instead a noun phrase "Snorkel breather".