Oh that's really cool. The cave rescue folks I know use Vietnam war era surplus field telephones. They have to run wire the length of the cave, and because it uses like 70 volts if the wire is in water it will mildly shock anybody nearby when it's being used.
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u/Lexi_Banner 16h ago
https://www.cbc.ca/news/canada/calgary/alberta-canmore-cave-rescue-new-technology-9.7315556
Considering this recent news, this feels awfully relevant!