The L.C.L Sea (ＬＣＬの海, "LCL no umi") may informally refer to the LCL-flooded seas following Third Impact, but it is used in a more specific context by Lilith/Rei Ayanami to denote, apparently, a metaphysical domain where life originated.
In the midst of human instrumentality, Shinji and Rei are depicted as one in a watery red domain with the Moon above, Earth below, and Black Moon, Sun, and stars on the horizon. When Shinji asks where they are, Rei responds :
- "This is the LCL Sea. (We are) inside the sea where life began. A world without A.T. Fields... without your own shape. An ambiguous world where it is impossible to tell where you end and other people begin. A fragile world where you exist everywhere, and thus exist nowhere."
The LCL Sea in question cannot be a physical place, which raises the question of precisely what it is. The souls being complemented reached this place by entering Lilith's Chamber of Guf , but it's unclear whether the Chamber of Guf and the LCL Sea are synonymous, or if they are simply connected, if one encompasses the other, etc.
- "The ultra-thin space is supported by an inwardly-directed A.T. Field. The inside is an imaginary space, called a Sea of Dirac. I think it's probably connected to another universe."
When Eva-01 shoots at Leliel's ultra-thin body, a fluid identical in appearance to LCL spurts out. Eva-01's bullets possibly broke through Leliel and briefly opened up the universe beyond, providing what may be an early intimation regarding LCL's ultimate origin. Hypothetically, then, the generation of a Dirac Sea provides a gate to "another universe" we know only as the LCL Sea. The Chamber of Guf may, accordingly, be a manifestation of the Dirac Sea phenomenon.
LCL sourcing from another plane of existence could begin to explain Lilith's apparently perpetual ability to bleed the fluid.