Uchuu Kuubo Blue Noah

Set in the year 2052, Earth has managed to find peace until the arrival of the Death Force - ruthless aliens from a dying solar system - who are desperately searching for a new home. Attacking the Earth with a massive satellite ship called Terror Star, the aliens proceed to terraform the planet to make it their own. For mankind there is one hope: it's up to Colin Collins and a small band of his fellow surviving students to crew a top-secret submersible vessel that can fight the invaders at sea or in space.

Note: Episode 1 is ~96 min minutes as opposed to the standard 24 minute long episode. It was later split into 4 episodes on streaming, home media releases and most western dubs.