Duplicants can finally swim. The Aquatic Planet Pack, the paid DLC for Oxygen Not Included, plunges colonies into a flooded asteroid built around marine biomes, underwater critters, submersible buildings, and a brand-new swimming mechanic that changes how dry land scarcity plays out.
Quick answer: The Aquatic Planet Pack is available now on Steam, WeGame, and Epic for $9.99, and you need the base game to play it. A free base-game update ships alongside it for all players.
What The Aquatic Planet Pack includes
The DLC opens with a new starting world called Marinea, a marine-themed asteroid split into four distinct biomes, each with its own ecosystem. You get new critters, plants, ranching buildings, elements, foods, and geysers, plus two new recruits. Klei worked with long-time ONI modder Aki on parts of the pack.
One of the new Duplicants is a starter named Kai. The other, Minnow, is an Unknown Duplicant who survived alone in the environment and only joins your colony once you complete the asteroid imperative.
| Detail | Value |
|---|---|
| Price | $9.99 USD |
| Platforms | Steam, WeGame, Epic |
| Release date | June 11, 2026 |
| Requires base game | Yes |
| Requires Spaced Out! | No |
| New starting world | Marinea |
| New Duplicants | Kai and Minnow |
Swimming and Duplicant changes
Swimming is the headline addition. The DLC adds a Swimming skill tree with Basic Swimming and Divemaster skills. Trained Duplicants can hold their breath longer and tolerate the cold temperatures of moving through liquid, which makes the underwater world survivable rather than lethal.
Suffocation no longer kills instantly. When a Duplicant runs out of breath, they become incapacitated instead of dying. Other crewmates carry them to an oxygenated area and perform CPR, giving you a second chance to save them. Breath is now shown as a plain integer, similar to Health, rather than a percentage.
Several effects were retuned. Eye Irritation now applies a Stress penalty instead of an Athletic one. Soggy Feet and Sopping Wet now carry a Stamina penalty with reduced Stress impact, and moving through deep liquid adds its own stamina drain. To help manage all this, a Breathing Station lets submerged Duplicants top up their oxygen between tasks.
The four new biomes
Each biome on Marinea introduces its own plants, critters, and resources. They build into separate production chains, so the world rewards exploring all of them.
| Biome | Highlights |
|---|---|
| Beach | Gum Palm, edible Sodicanes, Mussel Sprouts, Slogo snail, Blowter fish, Tidal Spring geyser |
| Reef | Pearl-producing giant clam, Starnacle and Petta Pouf plants, Beakon and Blowter fish, oxygen-producing Flue Coral, and milkable Seaquines |
| Kelp Forest | Tower Kelp and Kelpole critters harvested for Nori, plus Orehulls that can be sheared for Iron Ore |
| Abyss | Glo Squids, Tublia, Pinpoket and Bulbloom plants, Thermal Gas Fissures, and Polluted Brine Vents |
Diggable natural backwall tiles appear throughout the asteroid, adding mineral resources without taking up space needed for other features. Note that even digging a dirt backwall requires the starter mining skill.
Aquatic ranching and critter changes
Aquatic ranching gets a substantial overhaul, and some of it reaches the base game for free. The new Aquatic Critter Fountain and Fish Pick-Up are available to all players, while submersible versions of the Grooming, Shearing, and Milking stations are part of the DLC.
Critter happiness now matters more. The reproduction speed bonus for tame and happy critters scales with their exact happiness level, so happier critters lay more eggs. Pokeshells and Sanishells eat less per cycle, Pokeshell Molt mass is higher, and Sanishell sand conversion is faster. Non-fish aquatic critters no longer count fish when checking overcrowding.
Pacus were toned down after being overpowered. All Pacu morphs now produce less meat and smaller eggs, the eggs no longer drop Lime when crushed, and Pacu eggs no longer drop eggshells. The Fish Feeder also has less impact on critter happiness, which the new Aquatic Critter Fountain is meant to balance out.
New elements, buildings, and food
Rubber is one of the most useful new materials. It is produced at the Vulcanizer using Latex from the Gum Palm tree, and it crafts 4kW Insulated Conductive Wires, Rubber Boots that protect against Soggy Feet, and Gaskets that prevent unwanted liquid leakage. Many buildings that used Plastic as a secondary material now accept Gaskets instead.
Power and harvesting get new options too. The Tidal Turbine enables hydropower generation, and Marine Drills harvest built-up minerals from the Abyss geysers. A new Sushi Bar turns ingredients like Nori into dishes, and Seaquine milk (Ovolene) can be processed into morale-boosting Caviar, which also works as a dining-table garnish in place of Table Salt.
The pack adds new geysers in the form of Tidal Springs in the Beach biome and Thermal Gas Fissures and Polluted Brine Vents in the Abyss. New elements include Pearl, Rubber, Zinc and its variants, Latex, Polluted Brine, Galena, Basalt, and more. Over 100 cosmetic blueprints with a nautical theme are available through the Supply Closet.
The free base-game update
You do not need to buy the DLC to get some of the changes. The free update introduces a new bubble system where gases are carried from underwater sources to the surface of a pool before entering the simulation. Flatulent Duplicants now produce bubbles when farting underwater, and a plant in the Reef biome generates oxygen bubbles that turn into oxygen tiles when they reach a ceiling.
Liquid visuals were reworked across the board. Salt Water now appears blue with small crystalline specks, magma and molten metals have a more realistic texture, and objects sitting inside liquids are easier to see. The CPR rescue system, the breath integer display, and the new Aquatic Critter Fountain and Fish Pick-Up are all part of the all-versions update.
If you want to keep playing an existing colony, you can upgrade an old save from the pause menu by clicking the DLC’s logo, which creates a DLC-enabled copy. New worldgen features, including Marinea itself, apply only to new games. Backing up your save before switching over is the safe move.
