Like many others have already stated, this series is amazing.
Foreigners only started watching Korean series and movies due to the global success of Squid Game, and because of this, it's nearly the only series they know (maybe Hellbound too?). Therefore, we need to stop compairing everything to it. Koreans have been making amazing series and movies well before 2020/2021, and compairing all of them to Squid Game is like compairing apples and oranges.
That said, The Silent Sea tells the story of humans trying to find answers in a foreign world. This is not a story about fighting aliens and monsters, but about a team of people seperated from the world they know, struggling to find answers in a world they cannot comprehend. Bae Doona is, as always, remarkable! She takes on a role and makes it her new skin. Gong Yoo and all the other actors are great as well. You don't need a detailed script that explains the story for you. Sometimes the short dialogue or lack of lines allows the actor to portray everything you need to know.
If you're looking for an action-packed movie, no. There are intense scenes, but it's more of a thriller than an action movie.
This is a good series and definitely watch until the end, it's truly deserving of your time. CGI is beautiful and I can't wait for the release of the beautiful soundtrack. A lot of work was put into this and I'm thankful they were able to deliver this great series before the end of the year.