Israel has apparently used submarine sensor technology to develop and deploy an underwater detection system off the Gaza coast. Israel has been particularly effective at spotting and catching Palestinian terrorist scuba teams trying to smuggle weapons into Gaza. They caught another such team last week. Israel has said nothing about an underwater monitoring system, but one using acoustic and/or motion sensors, coupled with software to sort out the fish and other floating debris is well within the capabilities of Israeli counter-terrorist technology, is apparently in use. Usually Israelis sell such technology to foreign buyers, but the need to keep details of the system secret (to make it harder to bypass) would mean making those sales secretly. This is sometimes done when sensitive technology is involved.