I like Submarine movies. They play out in an environment that is hostile and archetypical thriller country. You don't need to do very much to create tension when there's several tonnes of water threatening to crush you at every moment.
So exactly why the writers of this series decided to make it into a melodrama is beyond me. This seems to have drawn less from such classics as Ice Station Zebra, Das Boot and The Hunt for Red October than it has from later season episodes of 'Voyage to the Bottom of the Sea' - yes, I am saying early VTTBOTS was better than this. Perhaps the producers really just wanted to tell a melodramatic story about a same sex couple with problems and decided to put it on a submarine when they were offered the use of the set. That's how an X-Files episode involving a submarine came about!