In the original Subnautica the most frequent request, going all the way back to the first Early Access version, was for an optional co-op mode. Because if you're going to be exploring an alien ocean filled with all sorts of horrible monsters that are just waiting for the perfect opportunity to scare the life out of you, why not add another few into the mix!
And so, now that Subnautica 2 has been officially announced, Unknown Worlds have revealed that they will finally be adding a fully fledged co-op mode. Best of all it'll support up to four players, so if you ever get attacked by some of the new leviathans you'll have a pretty good chance to escape... provided you're able to swim faster than your friends anyway!
Speaking of which, you can check out one of the new leviathans through the announcement trailer below. Have a gander:
Besides co-op, Subnautica 2 will bring with it all sorts of new biomes to explore, an expanded building system to let you create the perfect base, new critters of all sizes and dispositions, and perhaps most interestingly of all, the ability to "evolve your genetics to adapt your body for survival". Whether this is going to be a simple upgrade system or something else entirely, I have no idea, but I certainly wouldn't mind some gills when stuck in a seemingly endless ocean!
As for the release date, Subnautica 2 will be heading into Early Access at some point in 2025. The exact date hasn't been revealed just yet, but what I can tell you is that the current plan is for Subnautica 2 to spend around 2 to 3 years in development before finally launching in full. So if you're like me and you prefer the 100% completed and properly polished 'Version 1.0' experience, I'm afraid you're in for a bit of a wait.
Once more information becomes available, ideally alongside a proper gameplay trailer, I'll make sure to let you know. Until then, you can learn more about Subnautica 2 and Unknown Worlds' plans over at Steam.