Re: #2, that is active sonar, which is for useful for locating objects that are silent, e.g., rocks.[1] It also is very loud and disruptive for whales and dolp

Re: #2, that is active sonar, which is for useful for locating objects that are silent, e.g., rocks.[1] It also is very loud and disruptive for whales and dolphins.[2] [1] https://oceanservice.noaa.gov/facts/sonar.html https://oceanservice.noaa.gov/facts/sonar.html [2] https://skeptoid.com/episodes/4236 https://skeptoid.com/episodes/4236