The Blood Ocean was a large reddish sea located on the planet Ysmault that had served as a prison for the Guardians of the Universe. On this world, they imprisoned the demonic members of the Five Inversions terrorist cell which included Atrocitus. These beings were left on the planet to serve their sentence whilst the world was forbidden for anyone to approach. Following the Sinestro Corps War, Atrocitus killed his comrade Qull and used his blood to annoit the first Red Lantern Power Battery. With this at hand, he used it to create his Red Lantern Corps by harnessing the Red Light of Rage who quickly took the world as its headquarters. The Red Lanterns avoided entry into the Blood Ocean as they were all damaged and traumatized beings which was why they were consumed with rage to avoid the pain by wearing their Red Power Rings. As a result, entry into its red waters had the effect of forcibly reliving their trauma and restore their sentience once more. Its crimson waters were deep with many fearing further exposure to its contents though future usage allowed some level of immunity to its effects.
As a result of the War of the Green Lanterns, the mad Oan Krona was killed at the hands of Hal Jordan thus ending his control over the Green Lantern Corps. In honor of his pact with Atrocitus, Ganthet gave the corpse to Atrocitus on Ysmault. During this time, the Red Lantern leader began to experience increasing difficulties in controlling his rabid enraged Corps. Thus, he decided to restore the intelligence of one of his followers and make them his lieutenant. This saw him tricking Bleez to meet him and throwing her into the waters of the Blood Ocean which forced her to relive her painful experiences. Barely surviving, her sentience was returned to her where she began the process of working with the other Red Lanterns. Afterwards, Atrocitus encountered Skallox moving to meet with Bleez and ambushed the Red Lantern where he sampled his memories by drinking his blood. Believing a possible conspiracy being made against him, he decided to throw Skallox, Zilius Zox and Ratchet into the Blood Ocean in order to restore their intelligence where they experienced their traumatic pasts once more. Bleez was worried that the three may have ended up dying whilst going through their pain in the red waters. She was later responsible for entering the Blood Ocean once more in order to bring the three Red Lanterns to the surface where they regained their memories as well as former personalities whilst their master Atrocitus sought to find Krona who was seemingly alive as well as hiding on Ysmault. Abysmus emerged from the Blood Ocean after devouring Krona's corpse and shortly afterwards poisoned the Red Lantern Central Power Battery.
Following their confrontation with the Third Army, Atrocitus had the remains of one of the creatures taken with him back to Ysmault. Once there, he bathed it within the Blood Ocean in order to use his Blood Magic to discern its nature and origins. From the magic he used, he determined their creation by the Guardians of the Universe and that these creatures nature meant that they assimilated organic life.
Upon his addition to the Red Lantern Corps, Guy Gardner was dropped into the Blood Ocean by Rankorr during Bleez's denial of it as a good idea. Some time later, Supergirl, at the time a newly minted Red Lantern, was brought to Ysmault and, with the aid of the Green Lantern Corps and the Red Lanterns, was dunked under as well.