The story is quite heavy in Subnautica: Below Zero, and as you progress, you'll need to find your sister's job site and complete her job.
Finding the Frozen Leviathan differs by a fraction depending on where your Drop Pod lands, but the Frozen Leviathan is still in the same place - in the Glacial Basin.
The Seatruck must be crafted with the Seatruck Depth Upgrade MK1 and a cold suit to equip before going on a trip.
From your starting biome Twisty Bridges or the Drop Pod, its location is northwest of the Glacial Basin at the Phi Excavation Site. From our starting location / drop pod, go southwest about 1000 meters until you start seeing eye jellies.
Related: How to Find Marguerit Maida's Base in Subnautica: Below Zero
You will see a huge ice wall/structure in this area. You have to swim to the bottom of the ocean about 120m+ deep and find a path below. If you are in the right place, many eye jellies are grouped together, so be careful not to hit them.
Underneath this structure is a cave you need to enter, but it's easy to get lost in it, and of course the Eye Jellies are still floating around. Once in the cave, stay in the elevated section. If a path descends lower, do not take it. Eventually they will be an opening above you that you can take.
Once on the freezing ground, look northwest and there will be a cave entrance with glowing lights outside. Enter it and keep to the left to find the exit to an area called Glacial Forest, full of purple trees. From the exit of the cave. Head northwest until you see a radio communications tower in front of you.
To the left of this tower is another cave. Cross it, follow the path and you will find the frozen Leviathan.
If you wanted to find it without exploring it, here are the coordinates of the location -1619 29-763. Use the console command – warp -1619 29-763
If you're having trouble finding materials, here's how to find diamond in Subnautica: Below Zero or where to find lodestone!
