Mine is probably the most boring: There are many intelligent species in the universe. Faster-than-light travel, however, really is simply impossible, meaning that there cannot exist a truly interstellar civilization. So while some species have probably settled solar systems other than their own through generation ships, suspended animation, time dilation, or whatever, their range of expansion is limited. This means that encounters between species of different planets are rare. Humans will most likely never contact any intelligent alien species, at most one or two. We might, however, discover evidence of their existence through telescopes or something.
Yeah, any species that might develop in an ocean on an ice planet might never even know space exists because they wouldn't be able to see the stars, for example.
That brings up an interesting question. Should we ever make contact with such a species? I mean first for such a species to exit their planet they would A) need to evolve/gene-splice themselves to survive with Oxygen(or any air that they'd like) or B) Create ships with giant water tanks and only colonize the oceans of planets
Also it'd be cool if we could find such a species and co-habituate the universe with. We take the land, they the ocean