The Cosmic Ocean is a twisted adaptation of every world in the game, with each level having a theme of a specific world. A player can find themselves back in a broken up recreation of Dwelling, Jungle, Volcana, Tide Pool, Temple of Anubis, Ice Caves, Neo Babylon, and even Sunken City.
Each level is always of varying width and height, and loops around within itself both vertically and horizontally. This means that if a player falls down in a level of the Cosmic Ocean, they will end up at the top of it.
Despite what the player may assume from their experiences with rope not functioning without a proper wall in the Duat, Rope will function perfectly normally, even if clinging to the black nothingness of the Cosmic Ocean. This also means that enemies that cling to walls like Grub will function normally as well.
Many of the level generation rules that normally apply in the standard worlds do not apply in the Cosmic Ocean. This means that a player can potentially be in danger the very second they enter a new level, such as a Crush Trap appearing just above the entrance of a Temple of Anubis-type level, or an Elevator appearing above the entrance of a Neo Babylon-type level.
There are 95 levels the player must beat to reach the 3rd ending of the game, culminating to 7-99, where they will become one with the cosmos and leave behind a Constellation.
Unlike the standard levels found in the rest of the game, A Celestial Jelly will be blocking the exit door, vaporizing any player that gets too close. In each level, 3 celestial orbs will spawn. When all of the orbs are destroyed, The Celestial Jelly will move away from the exit and begin moving towards the player in an attempt to stop them from leaving the level.
Shops, Pets, Curse Pots and Kali Altars will NOT spawn in the Cosmic Ocean under any circumstance. No Kali Altars or Pets means that if the player is Poisoned or Cursed, the only way to remove the affliction is to die.
- If the player made it to the Sunken City with plenty of bombs and rope, likely attained from the bag awarded after completing the Sun Challenge, it is recommended that they make liberal use of them, as they will prove useful for making shortcuts through the level to the exit, climbing up to the bottom of the level, and other helpful uses.
- On top of this, the player will never have a use for them again after completing the Cosmic Ocean, so they have no reason not to use these resources unless they are low on them (~10 or less).
- One should take advantage of the time that they have in each level, as 3 minutes is more than enough time to locate the exit, all three celestial orbs, and devise a plan of exiting the level after destroying the last orb and triggering the Celestial Jelly.
- One strategy is to not destroy any orbs until the player has planned which orb should be the last one they destroy and have a solid route to the exit after doing so, while another strategy is to destroy all three orbs as quickly as possible, and deducting the location of the exit door by seeing which direction the Celestial Jelly comes from.
- Making contact with a Celestial Orb will stun the player if they did not stomp on it, meaning they should make sure to avoid embarrassing deaths by not running towards it too quickly.
- When traveling on the edges of Cosmic Ocean levels, the player should become aware of any possible threats that may suddenly appear and/or spend as little time on the edges as possible. This is because random falling enemies and objects can easily be a death sentence for the player.
- Random falling Cat Mummies and Crush Traps in Temple of Anubis-type levels can easily get the player killed in a matter of seconds.
- Falling, flaming enemies like Olmites flung by Spark Traps and Magmars can easily lead to the player's end if they are wearing a flammable pack-item like a Jetpack.
- Being hit by an Arrow Trap in either Dwelling or Sunken City-type levels that lie on the edges of the level will stun the player and send them infinitely falling until they hit a part of the level, which will always kill them, even at 99 HP.
- Rolling Horned Lizards can also cause a fall of this magnitude by flinging the player far into the open space or hitting the player on their way down as they fall through the void.
- One should be wary of any potential hazards around the exit of a Cosmic Ocean level. Enemies, Crush Traps and other hazards may hide within a Celestial Jelly blocking the exit.
- The player should be extremely careful in levels containing enemies who can curse or poison them, particularly in Temple of Anubis-type levels, where both are present in the form of Cobras and Cat Mummies. Other sources of curse/poison include Witch Doctors in Jungle-type levels, Scorpions in Pots, and Hermit Crabs in Tide Pool-type levels.