World of Warships is an arcade game. This is not a secret.
The ships are artificially large in appearance vs. the range they fire at to make the game feel more approachable. IRL naval battles would not make for an easy game that fits 12 v 12 within 20 minutes.
There are going to be some things that don't perfectly align with the "Real World" so that they can fit into the game that we play. This is just reality!
Submarines moving faster underwater or on the surface even than they would in real life is just one of those realities to keep up with a faster-paced game.