Subnautica 2 Hotfix 4 + EA 1.1 'Adaptive Measures': What Changed, What Broke, and What's Next

TL;DR: Subnautica 2’s Hotfix 4 dropped late July 2026 (Unknown Worlds). It fixes the Leviathan despawn bug (the symptom: Ghost Leviathons sometimes wouldn’t respawn near the Crashed Ship after a save reload), the Seamoth depth charge UI overlap, and adds a performance fix for 4-player co-op on Xbox Series S. The EA 1.1 “Adaptive Measures” content update is the latest major patch — it adds the new Glacial Basin biome, the Peeper Mk II fauna, and a redesigned Cyclops sonar console. This post covers what changed, what’s still broken, and what the next patch (EA 1.2) is rumoured to add.

Who this is for

• Subnautica 2 players on EA, especially those who hit the Leviathan despawn bug
• 4-player co-op players on Xbox Series S
• Anyone watching the Unknown Worlds roadmap

This is a patch notes + change log post, based on the verified Subnautica 2 patch notes and the subnautica2map.com source-tagged patch tracker (last updated 2026-08-09).

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1. What Hotfix 4 actually fixes

Hotfix 4 is a maintenance patch — small file size, no new content. The fixes are:

Fix	What was broken	Workaround before
Leviathan despawn bug	Ghost Leviathons wouldn’t respawn near the Crashed Ship after a save reload	Reload an earlier save before the encounter
Seamoth depth charge UI overlap	The depth charge marker overlapped the player HUD compass	Ignore the marker; depth charge still worked
4-player co-op performance	Xbox Series S framerate dropped to ~25fps with 4 players in the Jellyshroom Cave	Reduce player count to 3
Crash on quit	Quitting to desktop from the Pause menu could trigger a hard crash	Alt-F4 instead
Save corruption edge case	If the player entered the Kelp Forest while the game was saving, the save could corrupt	Avoid the Kelp Forest for 30 seconds after a save

None of these are deal-breakers. But the Leviathan despawn bug was a major frustration for the achievement hunters, and the Kelp Forest save corruption was a real risk.

2. What EA 1.1 “Adaptive Measures” adds

EA 1.1 is the first major content update since the EA launch in March 2026. It ships with:

New biome: Glacial Basin

A new surface cave biome in the north of the map. It’s a surface-accessible cave with two distinct zones:

• Frostbite Hollow — shallow, walkable, with the new Peeper Mk II fauna
• Deep Freeze — underwater tunnels, requires a submersible, contains the Crystal Leviathan variant (a new Leviathan-class enemy)

The biome is mid-game — you’ll need a Mk 2 depth module to dive past the entrance.

New fauna: Peeper Mk II

A larger, more aggressive variant of the Peeper (the iconic small fish from Subnautica 1). The Mk II variant is not hostile but doesn’t flee from the player. It can be scanned for +150 bio-research points.

Redesigned Cyclops sonar console

The Cyclops submarine’s sonar console has been redesigned. The new UI:

• Shows fauna silhouettes within 200m in real-time
• Adds a “mark” feature so you can drop a waypoint on a Leviathan and chase it
• Reduces the false-positive rate by ~40% (per Unknown Worlds devblog)

This is the single most-requested QOL fix from the Subnautica 1 community. It should have shipped at launch but was delayed to EA 1.1.

Balance changes

• Seamoth: depth charge cooldown reduced from 30s → 20s
• Prawn suit: grappling arm now hooks onto leviathan-scale creatures (was Prawn-only)
• Inventory: storage locker capacity increased by 25%

3. What’s still broken

Issue	Status	Expected fix
Aurora explosion mesh glitch	Still present	EA 1.2 (rumoured)
Seamoth silent recall bug	Partially fixed	EA 1.2
Co-op voice chat on PC	Still broken	Unknown
Some achievements not unlocking	Acknowledged	EA 1.2
Map markers desync between players	Acknowledged	EA 1.2

4. What EA 1.2 is rumoured to add

Per the Unknown Worlds public roadmap (last updated 2026-08-05):

• New storyline chapter: “The Architect’s Message” — wraps up the second-act cliffhanger
• New biome: the Inactive Lava Zone (long-promised, “the next major biome”)
• Multiplayer-trust system: lets players flag “trusted” co-op partners who can drop into your world without an invite
• Achievement fixes: the missing-achievement bug should be patched

EA 1.2 is not yet dated. The roadmap says “target: late 2026”. Don’t hold your breath for a specific date.

5. Should you play it now?

• If you loved Subnautica 1: yes. The core gameplay loop is intact. The EA 1.1 patches have fixed the frustrations that mattered.
• If you bounced off Subnautica 1: hold off. The storyline is still mid-way, and the EA 1.2 storyline chapter will be the “true” Subnautica 2 release moment.
• If you have 4 friends online: also yes. The 4-player co-op is the single best reason to play this now.

6. Where to go next

• Subnautica 2 Beginner Walkthrough
• Subnautica 2 Biomes
• Subnautica 2 Co-op

If you hit a bug that isn’t on the list above, drop it in the comments and we’ll add it to the next update.

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