Looks like alkaline glaze and my first thought (I'm sure you've already thought of this) is canteen. But never seen a pottery canteen? Very nice condition!
Nice flask trk5capt.SWR,you sound like you know what your talking about with this so would you care to elaborate on how you came upon this conclusion,for those of us who are not "in the know"? The part about the Netherlands that is.Thanks in advance.
John, by the looks of that flask, I can tell it came out of pluff mud, beautiful shape and glaze. Here's a pic of a jug I found with a very similar spout/mouth to your flask. If SWR is correct, these relics may have been dumped off a Dutch ship that happened to be in port. Still has some oyster shell on the handle (I was scared to remove the rest) It's also in perfect condition! Came from the spot I mentioned in my PM to you. Again, beautiful flask!