Heh, to think the Germans wanted to build submarines running on 200+ tons of concentraded hydrogen peroxyde.
At home I have a few flasks of 50% stabilized hydrogen peroxide I use for bleaching wood and decapping paint off models. Even if it's stabilized, dropping reactive metals like copper or silver in it will result in a nice fountain spray, just like a shaked bottle of Coke. Dense fumes of pure oxygen will develop from the boiling liquid
It's also quite corrosive to the skin and it will ruin any tissue it will come in touch with. Nice substance!