Trongle Explained

Trongle is a device used on submarines to help swimmers, especially the naval special forces, to locate a submerged submarine in order that they may return to it. The trongle was invented by Captain John Moore of the Royal Navy.^[1]

Notes and References

1. https://www.telegraph.co.uk/news/obituaries/military-obituaries/naval-obituaries/7960494/Captain-John-Moore.html Captain John Moore obituary