The one piece hi-rez STL file for 3d printing can be downloaded below,
There is also a multi-piece STL package which will enable you to make a better and easier print. Also you’ll have an animated model with opening side cover, rotating propellers etc.
You can get it from here.
If you like, you can get 3 submarines for the price of 2. Click this link to get the Delphin, Turtle and Zeeteyfel as a bundle with reduced price.