I am reading an article on Science about collecting sound of underwater species, which is in the Q&A form. Part of this article says:

Q: Do your hydrophones ever … float away?

A: Oh yeah. In a freshwater bay, I had one I’m pretty convinced someone dragged away. We don’t mark them—otherwise curious people pick them up—but I had a ground line running along [this] hydrophone so I could find it later. I think someone [accidentally] put their anchor down and dragged it off somewhere.

I don't understand what the interviewee mean by "ground line" here. I cannot imagine what "a ground line running along [this] hydrophone" describes.

  • 1
    A line here is A length of cord, rope, wire, or other material serving a particular purpose. The device has no marker, so a line is attached to the shore so that the owner can find it later. To ground something is to Connect with the ground. Commented Feb 26, 2022 at 16:59
  • I think he means the same thing as a ground cable. However, I don't see how putting one along the hydrophone helps to locate it unless the cable has some electronics in it.
    – Lambie
    Commented Feb 26, 2022 at 17:52

1 Answer 1


A groundline is part of a fishing setline that anchors the set to the bed.

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It sounds like similar equipment was used to anchor the recording equipment underwater.

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