To unlock the Tadpole's schematic, you'll need to successfully scan three distinct fragments. While more exist, focusing on these five early-game locations will streamline your acquisition process.
Begin your search just north of the Old Habitat's wreckage, approximately 370 meters directly north of your Lifepod. This is a key area where NOA will direct you to find Quaker's black box. Upon reaching the ruins, venture slightly northwest into a ravine where a crashed Tadpole awaits, conveniently near the entrance of the ruins. Remember to also scan other valuable items like the Sonic Resonator, Processor, and Scanner Station in this vicinity.
An additional fragment can be found in a ravine situated 280 meters northeast of your Lifepod. This is also a good spot to find lead, crucial for the Sonic Resonator. Navigate northeast following a 75° bearing until you encounter a natural blue current. Descend into the ravine using this current, and you'll find a colony ruin platform to your left, with the Tadpole fragment nearby.
For the final fragment, head towards the edge of the abyssal crater, near 'The Great Jaw'. This area is at a greater depth, so it's advisable to enhance your oxygen capacity using Air Bladders and the Standard Air Tank upgrade, and consider the Wakemaker for faster movement. From the Lifepod, travel northeast, dropping off the shelf and following the wall down to the crater's edge. Here, amidst scattered colony wreckage, you'll locate the last Tadpole fragment.
Once all fragments are scanned, the next step is to establish a Moonpool within your base. Ensure you build a spacious room with ample clearance beneath, as the Tadpole Dock extends significantly downwards. A Vehicle Fabricator must also be attached to the side of the Moonpool. The total resources required for this setup are 5 units of titanium, 4 titanium ingots, 2 copper wires, 2 glass, 1 copper ingot, and 1 silver ingot. Ingots can be processed using your base's Processor facility.
With the Moonpool and Vehicle Fabricator in place, you can proceed to craft your Tadpole. This requires 2 titanium ingots, 1 glass, 1 system chip, and 1 power cell. While most materials are easily sourced, the power cell demands Strong Acid and salt. Strong Acid is best harvested from Necrolei Cysts in the jelly forest near the Old Habitat, while salt is readily available in the cave housing Chap's habitat and black box. It's also wise to craft an additional power cell for unforeseen circumstances and prioritize unlocking the Repair Tool to maintain your Tadpole against marine life encounters or accidental collisions.