Fascinating WW1 U-Boat footage
 

Need a Netflix membership to see it, but it's "instant watch" (no need to wait for a DVD), so even a preview membership lets you take a look.

ANYWAY, it's "The Log of the U-35" on this page:

World War I Films of the Silent Era

Obviously somewhat pieced together, but overall a very impressive production, given the period. I don't think I've seen motion picture of this many WW1-era subs, freighters, and warships anywhere else.

I have this movie too. Such footage is ultra rare. I can't even describe the feelings I get when whatching it. It is like being put back in time. Personally I experience such footage very different than WWII.

This is something very special and not just because it is rare.