Re: Ocean Floor Civilization

They may be able to hear powered shipping and/or submarines, but I think
the dead giveaway would be laying a communications cable through one of
their cities. Or having the Titanic fall on them.

If they rely on sonar (like our cetaceans), and the landlubber ships
produce sonar (like our submarines), the oceangoers should be able to
detect landlubber ships from hundreds of miles away.

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