Subnautica 2 heat barrier stops you cold around 250 metres from your starting Lifepod. The ocean floor shifts into an underwater desert biome and your PDA immediately tells you to back off. Stay too long and you will die. To get through it, you need the Heat Tolerance Adaptation – a permanent biological upgrade that lets your character survive high-temperature water. This guide covers exactly how to get it, step by step.
You can explore the game right now via Subnautica 2 on Steam or on Xbox Game Preview. For more on the game, visit the official Subnautica website.
TL;DR
- The heat barrier appears roughly 250 metres from the Lifepod. You will see a red half-circle indicator with rising temperature on your screen.
- You need the Heat Tolerance Adaptation to pass through it safely.
- Heat Tolerance comes from an Angel Comb, but only after you clear all connected Bloom Cankers.
- You must craft the Sonic Resonator first. Bloom Cankers cannot be destroyed any other way.
- Scan two Sonic Resonator fragments near the Old Habitat to unlock the blueprint.
- Clear Bloom Cankers across one adult Angel Comb and two juvenile Angel Combs to unlock the Adaptation.
- The Angel Comb is about 200 metres northwest of the Lifepod at roughly 300 degrees on the compass.
- After getting Heat Tolerance, watch out for thermal vents in the hot biome – those still deal damage.
What Is the Heat Barrier in Subnautica 2?
The water around your Lifepod sits at roughly 20 degrees Celsius. Comfortable and safe. As you move toward the desert-like biome to the southwest, the temperature climbs fast. You will see a red half-circle icon appear on your screen with a number rising anywhere from 30 to 80 degrees as you get closer.
By default, your character has no protection against heat. Getting too close will drain your health. The game is not broken – it is gating this biome behind a biological upgrade you have to earn. That upgrade is called Heat Tolerance, and it is one of four Adaptations available in the current Early Access build.
Adaptations are permanent changes to your character’s biology. They are not crafted gear you can swap in and out. Once you have Heat Tolerance, it stays with you forever and you can freely enter the hot biome any time. For more on how Adaptations work in general, see our guide on how to get the Heat Tolerance trait in Subnautica 2.
Step 1: Craft the Sonic Resonator
Before you can do anything with the heat barrier, you need the Sonic Resonator. This is the only tool that can destroy Bloom Cankers – the infected nodes blocking the Angel Comb that gives you Heat Tolerance. Without it, you cannot progress.
To unlock the Sonic Resonator blueprint, you need to scan two broken versions of the tool in the ocean. The easiest place to find both fragments is near the Old Habitat, located roughly 300 metres north of the Lifepod. One fragment is on a side table near an airlock. The second is in an adjoining room on the floor.
Once you have the blueprint, craft the Sonic Resonator at your base Fabricator – not the basic one inside the Lifepod. The crafting recipe requires:
- 2x Titanium Ingot (craft at the Processor using 3x Titanium each)
- 2x Lead
- 1x Wiring Kit (crafted from Silver and Copper Wire)
- 1x Basic Battery
Lead can be found in ravines near the Old Habitat and starting area. For Titanium, see our guide on how to get Titanium in Subnautica 2. For Silver, check where to find Silver. If you have not built a Processor yet, read our guide on how to build a Processor and craft ingots.
You will also need a proper base with a Fabricator to craft the Sonic Resonator. If you have not set one up yet, see our guide on how to unlock the Habitat Builder and start building a base.
Step 2: Find the Angel Comb
The Angel Comb you need for Heat Tolerance is located roughly 200 metres northwest of your Lifepod, at about 300 degrees on the compass. Look for the Wander Blackbox signal – that marker leads you directly toward it.
Head southwest from your Lifepod and look for a tunnel leading downward at around 35 metres depth. Swim down into it and you will enter a large cave. The Angel Comb is inside – a massive plant-like structure sealed shut by Bloom Canker infection.
Do not interact with the Angel Comb yet. It will not open. You need to clear all the Bloom Cankers first. Interacting early does nothing – many players think it is bugged at this point, but it is working correctly.
Watch out when you arrive. The area around the Angel Comb has aggressive creatures including Marrowbreach and Nibbler Mango that will attack if you get close. Make sure your health and oxygen are both in good shape before you start clearing. For oxygen tips, see our guide on how to increase oxygen in Subnautica 2. And if you want a High Capacity Air Tank for extended dive time, our guide on how to get the High Capacity Air Tank will help.
Step 3: Clear the Bloom Cankers
This is the core of the Heat Tolerance unlock. The adult Angel Comb has two large purple roots, or tendrils, leading away from it to two juvenile Angel Combs. All three combs – the adult and both juveniles – have Bloom Cankers you need to destroy.
Here is the order to follow:
- Enter the cave via the Wander Blackbox tunnel. Destroy all Bloom Cankers inside the cave on the first tendril.
- Follow that tendril out of the cave to the first juvenile Angel Comb, located roughly 240 metres southwest of the Lifepod at the Spider Dome POI. Destroy all the Bloom Cankers here.
- Retrace your steps and follow the second tendril to the second juvenile Angel Comb, roughly 240 metres north-northwest of the Lifepod. Clear the Bloom Cankers here too.
- Return to the adult Angel Comb chamber. Destroy the remaining four Bloom Cankers that now appear near the main comb.
- Interact with the opened Angel Comb to receive the Heat Tolerance Adaptation.
In total, you will destroy around eight to nine Bloom Cankers across the three infection sites. Your PDA will tell you when each area is fully cleared. If the Angel Comb still will not open after you think you are done, you have missed a canker somewhere. Follow each tendril carefully all the way to its end.
How to Use the Sonic Resonator on Bloom Cankers
Equip the Sonic Resonator, aim at the Bloom Canker node, hold the trigger to charge it, and then release. The charged sound blast destroys the canker. If you are struggling with enemies swarming you while you work, consider charging up and using a dash to quickly close the distance, destroy the canker, and retreat before more creatures aggro onto you.
For a full walkthrough of the Angel Comb puzzle including how it connects to the story, see our dedicated Angel Comb puzzle guide and our guide on the Angel Comb at the Alien Ruins.
What Happens After You Get Heat Tolerance
Once you interact with the Angel Comb and receive the Adaptation, the heat barrier is gone for good. You can enter the hot biome freely without taking heat damage. Your character’s biology has changed permanently.
However, one thing to be careful of: thermal vents inside the hot biome still deal damage if you get too close. Heat Tolerance protects you from the ambient temperature of the water, not direct contact with scalding vent blasts. Stay aware of your surroundings.
What Can You Do in the Hot Biome?
The hot biome opens up a significant portion of the map and several important resources. Key things you can now access include:
- Gold – found in the hot biome as ore deposits. See our guide on how to get Gold in Subnautica 2.
- Sulfur – a resource tied to geothermal activity. See our guide on how to get Sulfur in Subnautica 2.
- Tadpole Pens – the locked facility to the east where you find the Scout Ray Chassis and advance the story. You cannot reach this without Heat Tolerance. See our guide on the Tadpole Pens keycode and locked door.
- Story progression – Heat Tolerance is a required step on the main campaign path. Without it, you hit a wall in the narrative.
Common Problems and Fixes
The Angel Comb will not open after I cleared the Bloom Cankers
You have almost certainly missed a Bloom Canker. The comb will not flower until every connected node across all three infection sites is destroyed. Go back and follow each tendril from the adult comb all the way to its end. Check the juvenile combs again too. There are usually eight or nine total cankers across the whole route.
I am dying before I can clear the cankers
Check your oxygen first. A High Capacity Air Tank or the Improved Fins will help significantly. For swimming speed, see our guide on how to swim faster in Subnautica 2. If you keep getting killed by creatures, consider reading up on how to deal with hostile creatures before your next attempt.
I cannot find the second juvenile Angel Comb
Follow the large purple tendril roots outward from the adult comb. They are your navigation guide. Each one leads to a juvenile comb. If a root hits a wall or obstruction, look for an entry point nearby – sometimes a gap in rocks or a short swim around an obstacle. Your PDA markers and the Blackbox signals in the area also help you orient yourself.
What Comes Next After the Heat Barrier
Heat Tolerance is a major progression unlock, but it is only one step in a longer journey. After accessing the hot biome and the Tadpole Pens, the next big goal is building and upgrading your Tadpole to reach deeper areas. See our full guide on all vehicle upgrades and modifications in Subnautica 2 to plan your next steps.
You will also eventually need to fix the Alien Power Plant and solve other alien structures in the deeper biomes. For that, see our guide on how to fix the Power Plant and open the Observatory. And if you are still getting started, our Subnautica 2 beginner tips and tricks have everything you need to build a strong foundation before tackling the heat barrier.
For rare materials you will need in later crafting, our Metal Farm guide shows you how to set up a passive resource production system so you are never short on the materials that matter.
