What would it be like to crash land on an alien planet where the entire surface was nothing but ocean? Well, it means you're going to be doing a lot of underwater diving. This is Subnautica. The beauty of this exploration and adventure game is the vast underwater world you're about to explore. The games oceans range from sun drenched shallow coral reefs to treacherous deep-sea trenches. With such a big world, you'll need to manage your oxygen levels and other materials well if you want to explore it all.
But just because you can look around, doesn't mean that's your sole priority. Remember, you crash landed here, which means you need to survive as much as explore your surroundings! You'll need to build bases on the sea floor, then build them up until they're viable bases that can handle anything that is thrown at it, and a lot will be thrown at it.
Plus, as this is a living world, that means there's a lot of life to be found in it, and not all of it will be good. You'll need to be observant, and know what's around you at all times, else you'll be eaten. Outfit yourself with a special suit that can traverse these dangerous waters and navigate through danger without fear.
Much like the real world, the oceans of Subnautica cycle from day to night, and with each cycle comes new reveals, and new dangers. The time of day may change some creatures, so be ready for what might come.