The Tadpole is Subnautica 2's signature mid-game submarine — a compact, maneuverable craft that bridges the gap between the fragile Seamoth and the massive Cyclops. With six upgrade slots, a modular design system, and a wide range of compatible modules, the Tadpole can be configured for almost any mission profile. This guide covers every available module, their unlock requirements and material costs, the optimal upgrade order for progression, and the best loadouts for exploration, resource gathering, and deep-dive missions.
Tadpole Overview
The Tadpole features a base hull integrity of 200, a crush depth of 300 meters, and a maximum speed of 28 units per second. It has six upgrade slots organized into two categories: Internal Modules (4 slots) and External Modules (2 slots). Internal modules affect the submarine's systems — power, sonar, storage — while external modules add physical attachments like shields and propulsion boosters.
The Tadpole is unlocked via the Mobile Vehicle Bay after scanning three Tadpole fragments found in the Grassy Plateaus and Sparse Reef biomes. The fragments are located between 50m and 150m depth and are relatively easy to collect early in the game. Once you have the blueprint, the Tadpole can be fabricated at the Mobile Vehicle Bay for the following base cost:
- Titanium Ingot x3
- Lubricant x2
- Wiring Kit x1
- Battery x1
- Glass x2
Build your first Tadpole as early as possible, even before you have any upgrade modules. The base Tadpole's 300m crush depth already exceeds the Seamoth's maximum upgraded depth of 200m, giving you immediate access to the Grand Reef and Blood Kelp biomes.
All Upgrade Modules
Storage Module
The Storage Module increases the Tadpole's internal inventory capacity. The base Tadpole has 16 inventory slots. Each Storage Module adds 8 additional slots, up to a maximum of four Storage Modules for a total of 48 slots. Storage Modules use Internal slots.
| Module | Effect | Slot Type | Materials | Unlock |
|---|---|---|---|---|
| Storage Module | +8 inventory slots | Internal | Titanium x2, Copper Wire x1 | Seamoth Storage fragment scan |
| Storage Module Mk2 | +12 inventory slots | Internal | Titanium x3, Copper Wire x2, Silicone x1 | Grassy Plateaus wreck scan |
| Storage Module Mk3 | +16 inventory slots | Internal | Titanium x4, Copper Wire x3, Magnetite x2 | Grand Reef wreck scan |
Speed Module
Speed Modules increase the Tadpole's maximum velocity and acceleration. Each tier adds a flat speed bonus and improves the responsiveness of the thrusters. Speed Modules use External slots.
| Module | Effect | Slot Type | Materials | Unlock |
|---|---|---|---|---|
| Speed Module | +15% max speed, +20% acceleration | External | Aerogel x1, Copper Wire x2 | Kelp Forest wreck scan |
| Speed Module Mk2 | +25% max speed, +35% acceleration | External | Aerogel x2, Nickel x1, Copper Wire x2 | Lost River wreck scan |
| Speed Module Mk3 | +40% max speed, +50% acceleration | External | Aerogel x3, Kyanite x2, Nickel x2 | Inactive Lava Zone wreck scan |
Speed Modules stack additively. Two Speed Module Mk2s give +50% max speed, which is enough to outrun most Leviathans in a straight line. However, for maximum evasion, pair one Speed Module with one Shield Module — speed to create distance, shield to survive the hits you cannot dodge.
Scanner Module
The Scanner Module enhances the Tadpole's built-in scanner system, increasing the range and detail of environmental scans. This is essential for locating resource deposits, wreck fragments, and Leviathan positions at distance.
| Module | Effect | Slot Type | Materials | Unlock |
|---|---|---|---|---|
| Scanner Module | 200m scan range, basic material detection | Internal | Copper Wire x2, Glass x1 | Default unlock |
| Scanner Module Mk2 | 400m scan range, Leviathan detection | Internal | Copper Wire x3, Gold x1, Table Coral x1 | Blood Kelp wreck scan |
| Scanner Module Mk3 | 600m scan range, blueprint detection, resource density | Internal | Copper Wire x4, Ion Cube x1, Crystalline Sulfur x2 | Abyssal Plains wreck scan |
Shield Module
The Shield Module is the Tadpole's primary defense system. When equipped, the Tadpole generates an energy shield that absorbs incoming damage before the hull. The shield recharges over time when not taking damage. Shield Modules use External slots.
| Module | Effect | Slot Type | Materials | Unlock |
|---|---|---|---|---|
| Shield Module | 100 shield HP, 15 HP/s recharge | External | Magnetite x2, Titanium x2 | Grand Reef wreck scan |
| Shield Module Mk2 | 200 shield HP, 20 HP/s recharge, 10s invulnerability burst | External | Magnetite x4, Kyanite x1, Nickel x1 | Lost River wreck scan |
| Shield Module Mk3 | 300 shield HP, 25 HP/s recharge, 15s invulnerability burst, EMP resistance | External | Magnetite x6, Kyanite x2, Ion Cube x1 | Lava Castle wreck scan |
The invulnerability burst on Shield Modules Mk2 and Mk3 has a 120-second cooldown. Do not waste it on minor creature encounters. Save the burst for life-threatening situations: Collector Leviathan engulf attacks, Abyssal Stalker charges, or Volcanic Drake fire breath.
Depth Module
Depth Modules increase the Tadpole's maximum crush depth. Without upgrades, the Tadpole implodes below 300 meters. Depth Modules are essential for accessing the game's deepest and most resource-rich biomes.
| Module | Effect | Slot Type | Materials | Unlock |
|---|---|---|---|---|
| Depth Module | Crush depth 600m | Internal | Titanium x2, Lead x2, Glass x1 | Sparse Reef wreck scan |
| Depth Module Mk2 | Crush depth 900m | Internal | Titanium x3, Lead x3, Magnetite x2 | Blood Kelp wreck scan |
| Depth Module Mk3 | Crush depth 1300m | Internal | Titanium x4, Kyanite x2, Nickel x2 | Lost River wreck scan |
Recommended Upgrade Order
Resources are limited in the early and mid-game, so upgrading efficiently is critical. The following upgrade path is optimized for maximum survival and progression speed:
| Priority | Module | Why | Unlocks Access To |
|---|---|---|---|
| 1st | Depth Module | Double your depth limit immediately | Grand Reef, Blood Kelp Trench |
| 2nd | Scanner Module Mk2 | Leviathan detection at 400m | Safe navigation through dangerous biomes |
| 3rd | Shield Module | Survive 2-3 Leviathan hits | Lost River transit with confidence |
| 4th | Speed Module | Faster transit, better evasion | Reduced exposure time in dangerous zones |
| 5th | Depth Module Mk2 | Access to 900m biomes | Deep Lost River, Abyssal Plains edge |
| 6th | Shield Module Mk2 | Invulnerability burst for emergencies | Full Lost River exploration |
| 7th | Storage Module Mk2 | More inventory for deep farming | Efficient material collection trips |
| 8th | Depth Module Mk3 | Access to 1300m biomes | Inactive Lava Zone, Lava Castle |
| 9th | Speed Module Mk2 | Outrun Abyssal Stalkers | Abyssal Plains safe transit |
| 10th | Shield Module Mk3 | Maximum protection, EMP resistance | Lava Castle, Primary Containment |
The Depth Module is always your first priority. Every other upgrade is secondary because without depth access, you cannot reach the wrecks that contain the fragments for higher-tier modules. Depth unlocks everything else.
Best Loadouts by Mission Type
The Tadpole's six slots mean you must make meaningful choices about your configuration. Different missions demand different loadouts. Below are the optimized configurations for the four most common mission profiles.
Exploration Loadout
Optimized for mapping new biomes, scanning wrecks, and navigating Leviathan territory safely.
| Slot | Module | Purpose |
|---|---|---|
| Internal 1 | Depth Module Mk2 | Access to 900m biomes |
| Internal 2 | Scanner Module Mk2 | 400m Leviathan detection |
| Internal 3 | Storage Module | Basic storage for collected fragments |
| Internal 4 | Storage Module | Additional storage space |
| External 1 | Shield Module Mk2 | Emergency protection + burst |
| External 2 | Speed Module | Quick transit between points of interest |
This loadout prioritizes information and survival. The Scanner Module Mk2 gives you early warning of Leviathan positions, while the Shield Mk2 provides a reliable panic button. Storage is kept to two basic modules to save resources for more critical systems.
Resource Gathering Loadout
Optimized for maximum cargo capacity during extended farming trips. Best used in biomes you have already mapped and are familiar with.
| Slot | Module | Purpose |
|---|---|---|
| Internal 1 | Depth Module Mk2 | Access to farming depth zones |
| Internal 2 | Storage Module Mk2 | +12 slots (tier 2 efficiency) |
| Internal 3 | Storage Module Mk2 | +12 slots (total +24) |
| Internal 4 | Storage Module | +8 slots (total +32) |
| External 1 | Speed Module Mk2 | Fast transit back to base |
| External 2 | Shield Module | Basic protection for known routes |
This loadout maximizes inventory to 48 slots (16 base + 32 from modules), allowing you to collect enough materials for multiple crafting sessions in a single trip. The Speed Mk2 ensures you can make fast round trips between your farming zone and base. Only a basic Shield is needed because you should be using this loadout in mapped, familiar territory.
Deep Dive Loadout
Optimized for reaching the deepest biomes in the game — the Inactive Lava Zone, Lava Castle, and Primary Containment Facility. This is the endgame configuration.
| Slot | Module | Purpose |
|---|---|---|
| Internal 1 | Depth Module Mk3 | 1300m crush depth |
| Internal 2 | Scanner Module Mk3 | 600m scan, blueprint detection |
| Internal 3 | Storage Module Mk2 | Storage for rare materials |
| Internal 4 | Storage Module | Additional storage |
| External 1 | Shield Module Mk3 | Max protection, EMP resistance, 15s burst |
| External 2 | Speed Module Mk2 | Outrun Abyssal Stalkers |
Do not attempt the Abyssal Plains or Inactive Lava Zone without Shield Module Mk3. The Abyssal Stalker's charge deals 80 hull damage, and the Volcanic Drake's fire breath applies a stacking burn that deals 15 damage per second for 10 seconds. Only the Mk3 shield's EMP resistance and 300 HP capacity can keep you alive through these encounters.
Leviathan Evasion Loadout
A specialized configuration for players who need to transit through heavily infested Leviathan zones. This is the survivalist's choice.
| Slot | Module | Purpose |
|---|---|---|
| Internal 1 | Depth Module Mk2 | Access to Leviathan biomes |
| Internal 2 | Scanner Module Mk2 | Early Leviathan detection |
| Internal 3 | Scanner Module | Passive environmental scanning |
| Internal 4 | Storage Module | Space for decoy flares and medkits |
| External 1 | Shield Module Mk2 | Emergency burst + solid defense |
| External 2 | Speed Module Mk2 | Maximum evasion speed |
This loadout sacrifices cargo capacity for information and evasion. Dual scanner modules provide constant situational awareness, while the Speed + Shield combo gives you the best possible tools for surviving Leviathan encounters. Use this when you are navigating through the Lost River, Abyssal Plains, or any unmapped territory for the first time.
Upgrade Station Locations
Module fabrication requires access to a Modification Station, which must be built inside a Seabase. The Modification Station itself requires:
- Titanium x5
- Computer Chip x2
- Wiring Kit x2
For convenience, build Modification Stations at the following strategic locations:
| Base Location | Depth | Serves | Notes |
|---|---|---|---|
| Shallow Safe Shallows | 20m | Early-game modules (Depth, Scanner, Storage) | Close to starting area, easy to resupply |
| Grassy Plateaus Border | 100m | Mid-game modules (Shield, Speed, Depth Mk2) | Central location near multiple biomes |
| Lost River Entrance | 500m | Late-game modules (Depth Mk3, Shield Mk2-3) | Deep base needed for endgame fabrication |
Keep a fully-stocked Modification Station at your Lost River base. Many endgame modules require rare materials found only in deep biomes (Kyanite, Ion Cubes), so you will need to craft upgrades on-site rather than transporting materials back to a shallow base.
Summary
- Build the Tadpole early — its 300m base crush depth opens more biomes than any other early-game vehicle.
- Depth first, always — Depth Modules are the gateway to every other upgrade.
- Scanner second — Leviathan detection is the most valuable non-combat tool available.
- Shield third — Survivability enables everything else.
- Match your loadout to your mission — Do not use a farming loadout in unexplored Leviathan territory.
- Build deep Modification Stations — Crafting on-site saves enormous transit time.
- Save the invulnerability burst — It is a 120-second cooldown; do not waste it on minor threats.
The Tadpole is the workhorse of Subnautica 2's mid-to-late game, and mastering its upgrade system is the key to reaching every corner of the map. Upgrade smart, load out wisely, and you will be diving deeper and coming back safer every time.