Players must scan three Tadpole fragments located around old human structures and colony ruins to unlock the Tadpole submarine blueprint early in the game. These fragments can be found near the Welcome Center cliff ruins, Tadpole Pens, the Old Habitat, a ravine east of the Lifepod, and the edge of the abyssal crater [1, 2].
After obtaining the blueprint, players need to build a large room in their base and place a Moonpool to house the submarine. Constructing the Moonpool requires 5 titanium. Unlocking base building itself requires scanning two Habitat Builder devices near the Welcome Center, which grants access to base tools including the Habitat Builder needed for large rooms and the Moonpool [1, 3, 2].
The Tadpole is the first and most basic submarine available in Subnautica 2. It helps players explore deep ocean areas safely. To craft the Tadpole, players need 2 titanium ingots, 1 glass made from quartz, 1 system chip, and 1 power cell. A Tadpole dock must also be added to bases to recharge the submarine’s energy [1].
After progressing past the initial blueprint unlock, players can upgrade the Tadpole with a depth module. This upgrade increases its safe exploration depth by 200 meters, allowing dives up to 450 meters. The depth module blueprint is found near Ruby’s second blackbox, inside a cavern 270 meters southeast of the Alien Ruins marker, close to Ruby's Tadpole wreckage. Crafting the depth module requires a modification station, 2 enameled glass, 3 celestine, and 1 system chip. To install it, players interact with a modification hatch behind the submarine’s power cell slot [4].
Unlocking room blueprints necessary for base expansions requires scanning a Processor or finding the Room recipe data card in colony ruins. This allows creation of functional base parts needed for the Moonpool and vehicle fabricator essential to the Tadpole [5].
The sequence players follow starts with scanning fragments early in the game, followed by unlocking and building a base with a Moonpool. Next, crafting the submarine and dock is done, with the depth module and further upgrades coming after locating key story items like Ruby's blackbox. The upgrade to 450 meters depth marks a key milestone for deeper ocean exploration [s1–s5].
