In order to make this weapon you will have to get hold of the following materials:
Titanium, which you can obtain by splitting limestone outcrops on the seabed floor
Silicone rubber, which can be obtained by harvesting the Creepvine seed clusters. Creepvine Seed Cluster, which can be found, glowing underwater and on the vines in the kelp forest. To collect them, all you have to do is interact with them, and then use the manufacturer to make the silicone rubber.
Then, when you have both materials, you can make the knife at the manufacturer.
After reading this article on how to get a survival knife in Subnautica Below Zero, you can get the silicone rubber and titanium and you can make it and get the best out of the game.
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