Subnautica 2 Bloom Infestation Guide: How to Clear & Unlock Heat Tolerance

The Bloom Infestation is a spreading biological hazard about 200 meters northwest of your Lifepod. It looks like an aggressive fungal growth overtaking the terrain, and it’s blocking your path to one of the most important Adaptations in the game: Heat Tolerance.

Without Heat Tolerance, you can’t access Gold deposits, Sulfur areas, or Tadpole Pens. That means critical mid-game resources and crafting recipes are locked behind this obstacle. Clearing the Bloom is not optional if you want to progress.

Here’s exactly how to do it.

What Is the Bloom Infestation?

The Bloom is an alien biological growth that has spread across a section of the seabed northwest of the starting area. It’s organic — pulsating tissue, root-like tendrils, and bulbous growths covering rocks, coral, and the ocean floor.

The Bloom is held together by Bloom Cankers — core nodes that anchor the infestation. Think of them as the root system. As long as the Cankers survive, the Bloom stays. Destroy all the Cankers and the entire infestation collapses.

You can’t damage Bloom Cankers with regular tools or weapons. They’re resistant to physical damage. You need a specific tool: the Sonic Resonator.

Step 1: Build the Sonic Resonator

The Sonic Resonator is a handheld device that emits targeted sonic frequencies. Against the Bloom, it weakens the Cankers’ structural integrity so you can destroy them.

Getting the Blueprint

The Sonic Resonator blueprint is found through exploration. Scan data boxes and wreck fragments in the area between your Lifepod and the Bloom Infestation. The game places the blueprint along the path you’d naturally take when investigating the Bloom for the first time.

If you haven’t found it yet, widen your search radius around the Lifepod. Check every data box in a 250-meter radius. The blueprint is there — sometimes it’s in a spot you walked past without scanning.

Crafting

The Sonic Resonator requires mid-tier materials. You’ll need resources from the starting and near-starting biomes. Nothing requires deep diving. Gather what you need, head to the Fabricator, and build it.

Make sure your equipment is solid before heading to the Bloom. Bring:

Sonic Resonator (obviously)
Food and water — you’ll be out for a while
A healing item — Medical Gel Sacs or an Enhanced First Aid Kit
A light source — parts of the Bloom area are dim

Step 2: Locate the Bloom Infestation

From the Lifepod, head northwest. Swim approximately 200 meters. You’ll start seeing signs of the Bloom before you reach it — discolored terrain, stray tendrils, patches of unnatural growth on rocks.

The infestation itself is unmistakable. The entire area is covered in organic tissue. The water might look slightly different — murkier, with floating particles from the Bloom’s biological processes.

Take a moment to survey the area before diving in. Look for Bloom Cankers from a distance. They’re larger than the surrounding growths, often raised up on thick stalks or embedded in the center of dense tissue clusters. You’ll need to find and destroy every single one.

Step 3: Weaken the Bloom Cankers

Equip the Sonic Resonator and approach the first Bloom Canker. Use the tool on it. You’ll see a visual effect as the sonic frequency disrupts the Canker’s biology — it might pulse, crack, or change color.

The Sonic Resonator doesn’t kill Cankers in one shot. The process works like this:

Hit the Canker with the Sonic Resonator. It weakens.
The Canker becomes vulnerable. Its exterior cracks or opens.
Destroy the weakened Canker. Once vulnerable, you can finish it off with physical tools or continued Resonator use.

Each Canker takes multiple Resonator hits. Stay close and keep applying the tool. The Canker will eventually collapse.

Watch for Hazards

The Bloom area isn’t passive. As you attack the Cankers, expect:

Defensive reactions from the Bloom itself. Some growths release spores or toxins when disturbed. Stay mobile.
Aggressive fauna. Creatures in the area may be agitated by the Bloom or by your Sonic Resonator. Keep your head on a swivel.
Navigation confusion. The Bloom tissue covers normal terrain landmarks. It’s easy to get turned around. Periodically orient yourself relative to the surface or your Lifepod compass direction.

Step 4: Destroy All Bloom Cankers

There are multiple Cankers throughout the infestation. Missing even one means the Bloom persists. Clear them systematically.

Strategy: Work From the Outside In

Start at the edges of the infestation and work toward the center. This approach has two benefits:

The outer Cankers are usually less defended. Fewer surrounding growths, less hazardous terrain.
As you clear the edges, the Bloom starts to recede, giving you clearer sightlines to the remaining Cankers deeper inside.

Mark each Canker’s approximate location mentally as you scout. Then work through them one by one, moving inward.

Strategy: Divide and Conquer (Co-op)

If you’re playing with friends, split up and assign sections. With four players, each person takes a quadrant of the infestation. Hit all Cankers simultaneously and the Bloom falls apart faster than it can react.

In co-op, the Bloom’s defensive responses are the same — spores, toxins, aggro fauna — but with four people absorbing the pressure, no single player gets overwhelmed. Bring healing items regardless.

Step 5: Confirm the Bloom Is Cleared

Once all Cankers are destroyed, the Bloom dies. You’ll see it happening — the tissue withers, the tendrils retract, the water clears. The area slowly returns to its natural state.

Your PDA or HUD may confirm the clearance. Either way, the visual feedback is obvious. If patches of Bloom still remain, you missed a Canker. Search the area again.

Step 6: Find the Heat Tolerance Angel Comb

With the Bloom cleared, the Heat Tolerance Angel Comb becomes accessible. It was hidden or blocked by the infestation.

The Angel Comb is in the cleared area — you don’t need to travel far from where you fought. Look for the distinctive organic structure with a pink bulb. Interact with the pink bulb and your character absorbs the Heat Tolerance Adaptation.

Heat Tolerance is permanent and immediate. No further crafting or processing needed. You can now enter volcanic zones, geothermal areas, Gold deposits, Sulfur-rich biomes, and Tadpole Pens without taking heat damage.

What Heat Tolerance Unlocks

This Adaptation opens up a significant chunk of mid-game content:

Gold deposits — needed for advanced electronics and some base modules
Sulfur areas — required for certain crafting recipes
Tadpole Pens — a renewable food/resource source
Volcanic biomes — contain story progression elements, rare resources, and unique fauna for Biomod sampling

You’ve been working around these zones since the early game. Now you can walk right in.

Common Mistakes

Going to the Bloom too early. Without the Sonic Resonator, you can’t damage Cankers. You’ll waste food and water swimming around an infestation you can’t clear. Get the Resonator first.

Not bringing enough supplies. The Bloom fight takes time. Bring more food and water than you think you’ll need. Running out mid-fight means retreating to the Lifepod and starting the trek back.

Missing a Canker. If the Bloom doesn’t fully collapse after you’ve destroyed what you think is everything, there’s another Canker hiding somewhere. Check elevated positions, underneath overhangs, and inside dense tissue clusters.

Ignoring the Sonic Resonator after the Bloom. The Resonator has uses beyond the Bloom Infestation. Keep it in your inventory — it may interact with other objects or creatures later in the game.

Timeline

Here’s roughly when this fits into your playthrough:

Hours 1-2: Get the Digestion Adaptation, set up basic base
Hours 2-4: Explore, gather resources, find the Sonic Resonator blueprint
Hours 4-6: Build the Sonic Resonator, clear the Bloom Infestation, get Heat Tolerance
Hours 6+: Access mid-game zones with your new heat immunity

The Bloom is a skill check. It tests whether you’ve been paying attention to exploration, resource gathering, and tool crafting. Pass it, and the game opens up. Skip it, and you hit a wall.