If you’re looking to make special machinery like the prawn suit in Subnautica, you’re going to need to craft an advanced material called aerogel.
How to make aerogel in Subnautica
At first, aerogel might seem impossible to come by, since it must be crafted with two ingredients - gel sacks and rubies - that you probably won’t come across by accident. If you’re looking for gel sacks and rubies, though, we’ve got gel sacks and rubies. Oh, we’ve got them.
Subnautica - where to find gel sacks
Starting from your escape pod, you need to head between south and southwest. To do this by eye, you need to be heading in a straight line, starting from the mid point between your pod and the Aurora, and you need to head in the direction the Aurora’s engines are pointing.
Assuming you’re going the right way, you should pass through a creepvine biome and come out again on the other side in a sandy biome. Eventually the scenery will fall away and you’ll need to descend to around 200m in a rocky area. Eventually you should come to some blue balls glowing in the dark.
If you don’t find them shortly after descending, head west a bit, away from the Aurora. Gel sacks can be found around the base of the blue balls if you search around. If you don’t have a depth module for your seamoth, you might have to swim down to the grassy areas below, but you’re looking for small balls with glowing circles on them.
Let’s say you have some planters back at base - you only actually need one gel sack in this case. Plant a gel sack and you can get two seeds from one by hitting it with your knife. A third hit will dig it up, but you can keep hitting the new ones twice once they grow, infinitely growing your stocks of the material.
Subnautica - where to find rubies
You can actually find some rubies at around 200m depth at the area where you find the gel sacks, but you should be searching on the side of cliffs, rather than at the base of the blue balls.
Another good spot for rubies is to head slightly west of north from your life pod. You’ll pass through a creepvine biome on your way. Once it drops down, you will swim down to about 200m, passing an Aurora wreck as you go and eventually coming to some floating islands.
Some of these floating islands have small cave systems inside them and these are a guaranteed place to find rubies. Just swim through the caves with a torch and make sure you’re checking the above and below as you explore within.
Once you’ve got both ingredients, you’ll be able to craft aerogel from your fabricator and you’ll be a step closer to getting that prawn suit. The schematics for building the prawn suit can be found in the prawn bay aboard the Aurora.
For more, here's where you find the cargo rocket in Subnautica Below Zero.