I am really interested in naval warfare. Especially the period ranging from before WW1 all the way until after WW2. I love the big battleships, the aircraft carriers, just everything! I would love to research more on this topic. Everything from naval doctrines, naval tactics, ship types, famous ships and ship classes, all the different navies at the same, and so on!
What books do you guys suggest for someone interested in this? As a german I am especially interested in the german navy of WW1 and WW2 and the austrian navy of WW1 (they had a quite big navy)!
I can recommend a couple of books off the top of my head.
If you're interested in battleships, I highly recommend Robert Massie's Dreadnought. It goes into detail about Britain and Germany's naval buildup prior to the outbreak of WWI.
Massie's follow up Castles of Steel is superb and goes into detail about the naval war between Britian and Germany during WWI. Both are incredibly readable and very in-depth.
For aircraft carriers, one of the easiest recommendations I'll ever make is for Shattered Sword. It specifically covers the Battle of Midway which was a pivotal moment in the Pacific War as well as for the use and development of Aircraft Carriers. Jonathan Parshall and Anthony Tully do a really good job debunking some myths about the battle, as well as going into some amazing detail about how the USN and IJN carrier forces were built up and composed beforehand. If you've got an hour to kill, his lecture at the Naval War College is really good as well.