Once you have a Cyclops, spend some time exploring and getting to know it. If you find a large cavern with another leviathan and an alien base, you've entered the right place.
There is also an Ion Cube mining node inside, so make sure you bring your Prawn Suit in that far if you have the drill arm. Get to the drive core. It can't. You will be underground for a long time and while there are fish you can hunt down there, nothing down there can be made into water, so a plant that gives good amounts of water is vital. There are fragments for this out in the world, but if you had the bad luck of not finding them, there are fragments of it early on in the Aurora.
For those that haven't already seen the end of the Sunbeam's story, keep reading. These will likely be exacerbated as the bacterium takes hold. If you decide to make a large base somewhere, there are two things you really want to consider: Location and Components. Your Cyclops will not save you, they will attack your Cyclops. They can also shoot fireballs.
e_heumueller.
By this part of the game, other than more exploring, there is only one real push left in the game. Your crashed ship. More is great, but that is the bare minimum if you want to make the Ultra High Capacity Tank, upgrade your Seamoth depth module, and make one of the necessary tools to finally explore the Aurora and some of the sealed wrecks you've been seeing around. Which is good, because you're about to need them. Depending on where it is referenced you will hear it referred to as base integrity, hull integrity, or base hull strength. While trying to disable the gun I found out the planet is under quarantine and I'm infected with the bacteria. Avoid.
... HORRIBLE NEW BACTERIUM INFECTION TAKES OVER MAN'S BODY!? As the Player enters, it can be seen that the facility is in a damaged state, due to what is revealed later in the story. It's doable, but inefficient and inconvenient. It's time to go spelunking in the Lost River to find some of the new content! It is up to you if you want to use this upgrade or the Lightweight High Capacity Tank, but I've never found the minor speed increase from the Lightweight one to be worth it personally. Rescue isn't coming to you. Keep in mind that they CAN hurt your Seamoth. I won't tell you what will happen in case you're one of those people that likes to explore bad ideas just to see what will happen, but I will tell you that if you try to go off the map, make sure you left anything valuable at your base/lifepod and be prepared for the possibility of having to craft another Seamoth.
After months (since June 2016) of there being a large open area in the Active Lava Zone, the exterior placeholder of the Primary Containment Facility was added to full this space. You'll get a broadcast from the Sunbeam pretty early on. Only one gap will remain in their story for you, within their second underwater base. Degree of infection is dictated by story progression, not number of game days. And the nuclear reactor, while amazing and definitely my favorite power source in the game, uses materials that are going to be exceedingly rare for you right now.
If not, they are usually in wrecks pretty close outside of the shallows.
If the area you're in has rocky pillars and lots of red grass, you're in the right place. The entrance I always find easiest to locate and initially navigate is the entrance in the northwestern Blood Kelp Zone.
Incubation time is how long you have a infection before you start showing symptoms, it's not how long you have to live.
Seaglide: Optional. One last suggestion is making a decent amount of beacons to place down. As you get further along the story, the infection gets worse, but like I said, it doesn't actually do anything bad to you. Their presence in the base is enough. This could be considered kind of early for some people, but I find that even a small base early on can have its uses, especially close enough to your lifepod to still be able to use your radio and fabricator instead of having to build new ones. If you go below 100m, your oxygen begins to drain faster.
Scan two to learn the blueprint and make one as soon as you can. The Enzyme acts as a countermeasure to the bacterium, nullifying its effects, and eventually purging it from the body. That's what is obscuring our destination and is a good marker to keep an eye on to make sure you're going in the right direction.