O 19-class submarine

The O 19 class was a class of two submarines, built for the Royal Netherlands Navy by Fijenoord, Rotterdam. The ships were designed as submarine minelayer for operations in both European and colonies waters. The class comprised O 19 and O 20 and were the first submarines in the world to be equipped with a submarine snorkel that allowed the submarine to run its diesel engines while submerged. The submarines diving depth was 100 meters. These units were very similar to earlier Polish Orzel class submarines, with a reduced torpedo battery and 10 vertical mine tubes fitted on each beam.

Construction
The ships were originally laid down as K XIX and K XX but later renamed O 19 and O 20.