Compared to its main enemy - the Royal Navy - the German Hochseeflotte was smaller, despite the efforts of the naval construction programs started at the end of the 19th century. 

The core fleet of the German Navy consisted of the battleships (called Linienschiffe) and battle cruisers (Große Kreuzer) mainly operating in the North Sea. They should have engaged the Royal Navy in a decisive battle which took place in the Battle of Jutland in May/June 1916. But despite the strategies of naval planers on both sides, this battle did not had the decisive result as expected. 

Although this core fleet took most interest, the German Navy of WW1 was more. Small cruisers operated together with the battle fleet - and were used as merchant raiders in all oceans of the world. Emden, Dresden and Königsberg were among the famous ships of their kind, and were lot in the Indian Ocean, Pacific or the African coast.  
In the North Sea, torpedo boats were used for various tasks, offensive and defensive. Mine hunters tried to make secure paths through enemy mine fields and were often engaged by the British fleet or were lost by mine hits. 
U-Boats attacked allied merchant shipping, first according to the rules defined before the war, but later, the unrestricted U-boat warfare was declared and merchant ships were attacked without a prior warning.

All those different kind of ships are shown in this part of the website, with line drawings, technical data and their history of operations.