Once Human Isles of Abyss is a free ocean expansion that launches on October 22, 2026, which is October 21 for Pacific time. The official update notice schedules the launch for 4:00 PM PT (7:00 PM ET) on October 21. It arrives on PC, mobile, PS5 and Xbox Series X|S with cross-play and cross-progression. You build ships up to Mobile Sea Fortresses and sail five sea regions, and the final boss, The Sunken Lord, appears once the server’s Purification Progress hits 100%.
Summary: Once Human Isles of Abyss
- Release: October 22, 2026 (October 21 PT). The official notice lists 4:00 PM PT on October 21.
- Price and platforms: free on PC, mobile, PS5 and Xbox Series X|S, with Game Pass access.
- Crossplay: full cross-play and cross-progression across all platforms.
- Ships: craft and upgrade vessels, from skiffs to Mobile Sea Fortresses with artillery.
- Server goals: Calamity Towers and later Calamity content push the server toward the finale.
- Boss: The Sunken Lord unlocks at 100% Purification Progress. Its player count and mechanics need confirming at launch.
- Caveat: most gameplay details come from closed tests, so launch numbers may differ.
What Is Once Human Isles of Abyss?
Isles of Abyss is a new survival scenario for Once Human, and the studio calls it the largest content update since the 2024 launch. Instead of one connected landmass, players explore a cluster of scattered islands and the ocean between them. The expansion adds five sea regions, ship building, diving and a new endgame boss.
The story hook comes from the reveal trailer. A navigator named Malla, who says she has “drowned a thousand times,” warns players with six survival rules from her logbook. Those rules point to hazards such as predatory lighthouses and living islands. Behind them sits The Sunken Lord, an ancient entity that turns the sea itself into a threat.
Once Human is free to play on every platform, and Isles of Abyss is a free update. Therefore, you do not need to buy anything to join. You do need the base game installed and updated.
Release Date and Start Time in the US
Starry Studio announced the date as October 22 (Oct 21 PT), 2026. Those two dates describe the same moment, so Pacific-time players see the launch on the evening of October 21. A separate official update notice, posted for the September 28 patch, says the next update arrives on October 21 at 4:00 PM PT and that Isles of Abyss is about to officially launch.
Here is that time in each US zone, based on current information.
| Time zone | Launch time (October 21) |
|---|---|
| Pacific (PT) | 4:00 PM |
| Mountain (MT) | 5:00 PM |
| Central (CT) | 6:00 PM |
| Eastern (ET) | 7:00 PM |
The September 28 maintenance was expected to last about two hours, and the studio noted that the real server opening time can differ. As a result, expect a similar window and check the in-game notice on launch day. The same official notice also says an ocean map for RaidZone, called Isles of Abyss: RaidZone, arrives with the update.
A reservation event is live on the in-game event page, and the studio ties gifts to it. Reserve before launch so you do not miss them.
Platforms, Crossplay and Console Details
The expansion lands on every current platform at the same time. Console players are included from day one, which matters because Once Human only reached PS5 and Xbox Series X|S on August 25, 2026.
| Platform | Isles of Abyss | Notes |
|---|---|---|
| PC | Yes | Steam and Epic listings are official |
| Mobile (iOS and Android) | Yes | Part of the cross-play pool |
| PlayStation 5 | Yes | Full resource pack required for test builds |
| Xbox Series X|S | Yes | Game Pass members get immediate access |
Cross-play and cross-progression cover PC, mobile and console. In practice, you can start on one platform and continue on another with the same account. The studio did not list PS4, Xbox One or Switch versions in the sources we found.
Once Human Shipbuilding and the Mobile Sea Fortress
Ships are the headline feature. According to the official announcement, players craft, customize and upgrade vessels, from agile skiffs to massive Mobile Sea Fortresses. A ship can serve as a base, a workshop and a heavy artillery platform, so your design shapes how you handle ocean hazards.
The final test notes added several naval changes:
- Cannon wheel: you switch between cannons through a wheel, and the control camera was adjusted.
- Pre-aim line: cannons with projectile drop get a line that helps you land shots.
- Handling: water territories start moving more easily, and turning is less awkward.
One restriction is worth knowing now. The September 28 notice says Youngling Huts cannot be built in the RV or on water territories in Isles of Abyss. Plan your animal breeding on land.
Calamity Towers and Haywire Zones
The scenario ties every player to a server-wide clock called World Progress. These are the official systems behind it.
Calamity Towers. They activate in the ocean as World Progress advances. You rally allies, sail to the matching region and challenge the tower. The first time a server defeats one, every player on that server gets a reward mail, and World Progress gets an extra boost that speeds up Phase II. Towers also gain new challenge variations as progress grows.
Haywire Zones. These survival events give different island groups unique rules. Four were confirmed in the final test.
| Haywire Zone | What it does |
|---|---|
| Mist of Deceit | Mist limits your vision, and lower HP shrinks it further. Light-based items clear it. |
| Skyfire | Meteoric gold has transformed a volcanic region, with wealth hidden in the meteorites. |
| Time Rain | Plants and animals grow unnaturally fast, while items and gear wear down quickly. |
| Black Tide | Pollution surges in cycles, with Pollution Zones rising one after another. |
Later content differs by test. Earlier tests described Calamity Zones that appear after Phase II begins. The final test instead listed Calamity Nests, where the energy of the Calamity Owl spawns randomized layouts of strong enemies. Because the launch notes do not name either, treat both as unconfirmed for the final release.
Exploration, Diving and Voyagers
Survival spans three connected layers: the sea surface, the islands and the deep water. In the Abyssal Sea regions, players can find Treasure Maps that lead to hidden sites such as shipwrecks and sealed underwater laboratories.
Voyagers add random ocean events. These ships cruise random routes through the major waters, and you can destroy them or board them for loot. Larger ships with better facilities are harder, but they also drop better Loot Crate rewards. At night, more dangerous enemies appear on the islands, and Deviations still roam the wilderness for capture.
The Sunken Lord Boss Guide: What Is Confirmed
The Sunken Lord is the endgame dungeon, and the official details are short. It appears after Phase II of the scenario begins and once Purification Progress reaches 100%. That means the whole server’s Calamity clears decide when anyone can fight it.
The player count needs care. The most recent official test notice, for the final test that ran from September 16 to October 8, calls it a 4-player dungeon. Earlier coverage of the Pioneer Test described it as an 8-player dungeon. Based on current information, the 4-player figure is the newer one, but the launch version may change it again.
The studio has not published boss mechanics, because testers signed non-disclosure agreements. Therefore, any move list you see before launch is a guess. What you can do is prepare in general ways: upgrade your ship, since the official notes tell players to arm up and strengthen their ships for tougher ocean content, and push your server’s tower progress. We will update this section once launch players confirm the fight.
How to Prepare Before October 22
- Reserve on the event page. The studio ties launch gifts to the reservation.
- Update the game. The next patch lands at launch, so keep your client current and leave storage free.
- Practice controls. Ship cannons use a wheel, so try the layout on your platform first.
- Choose your server carefully. Each scenario runs on its own servers, so pick one that fits your schedule, because progress is shared.
For more guides and news, browse the GameSpec gaming news hub and the GameSpec guides section. You can also read the studio’s own final test notice on the official Once Human site.
Common Mistakes and Clarifications
- Mixing up October 21 and 22. They are the same launch moment, seen from different time zones.
- Assuming The Sunken Lord is 8-player. The newest official notice says 4-player.
- Treating test numbers as final. The final test was a data-wipe beta, and the studio said the content did not represent final quality.
- Expecting an exact maintenance length. Only the start time is official so far.
- Planning Youngling Huts on a ship. They cannot be built on water territories.
Conclusion
Once Human Isles of Abyss launches for free at 4:00 PM PT on October 21, with cross-play on PC, mobile, PS5 and Xbox. Ships, Calamity Towers and Haywire Zones form the core loop, and The Sunken Lord waits at the end. Reserve now, keep your game updated and expect some numbers to change at launch.
FAQs
When does Once Human Isles of Abyss release?
It launches on October 22, 2026, which is October 21 for Pacific time. The official notice lists 4:00 PM PT on October 21.
Is Isles of Abyss free?
Yes. It is a free update, and Once Human is free to play on every platform.
Does Isles of Abyss support crossplay?
Yes. The studio confirmed cross-play and cross-progression across PC, mobile and consoles.
Is it on Xbox Game Pass?
Game Pass subscribers get immediate access to the expansion at launch.
What is The Sunken Lord?
It is the endgame dungeon that unlocks after Phase II begins and Purification Progress reaches 100%. The newest official test notice calls it a 4-player dungeon.
What is a Mobile Sea Fortress?
It is the largest ship type. Players can build a vessel into a base, workshop and heavy artillery platform.
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