Hi Guys, My naval career was short and in the (beg pardon) the FAA. However, step son considers that I am the fount of all nautical knowledge. Here is his question, don't ask why he wants to know because he hasn't said! "Could early WWII submerged submarines gauge the depth of the sea they were in passively ie without the use of sonar or other technology which would betray their position to surface vessels?" I think he was asking about the depth below the boat, not the depth from the surface as I assume that pressure gauges would give that info anyway. I have been on either one or two Submarines, but both were alongside and definately not submerged. I can see that a guy standing on the bow with a line is out of the question (because I am fairly bright!) but I don't know how to answer him. Having been lurking for more than a few weeks, I do expect a variety of answers from fellow members. (be kind) I will appreciate any help. Mugfaker.