Underwater space opera

Three links on someone's "Metis" idea for a space opera franchise. Optimistic and liberal, but the key novelty is "what if your wormholes/jump gates/hyperspace rifts are underwater?" Suddenly your "spaceships" are submarines and lots of tropes make more sense.

https://forum.rpg.net/showthread.php?790255-Hypothetical-If-you-set-up-a-new-TV-Space-Opera-franchise&p=20452680#post20452680
https://forum.rpg.net/showthread.php?790255-Hypothetical-If-you-set-up-a-new-TV-Space-Opera-franchise&p=20453088#post20453088
https://forum.rpg.net/showthread.php?790255-Hypothetical-If-you-set-up-a-new-TV-Space-Opera-franchise&p=20454562#post20454562