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Warhammer(40k) Does the Imperium have any sort of navy?

Is there any kind if waterborne assult? Destroyers, Subs anything like that? Do any other factions have a sort of navy. I am aware that all of the space ships conventional ships might not be as practical but the warhammer universe has such an array of cultures and worlds there would probley be some sort of navy somewhere right?
gpt
There are planets with water-based defences, particularly on Death Worlds where there are dangerous aquatic creatures, like the sea serpents on Fenris. However, in terms of waterborne assault, there is pretty much nothing, since in practice spacecraft and aircraft blow anything else out of the water, if you'll pardon the pun.