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.[1] 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."[2]
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.
A possible clue comes from Leliel, about whom Ritsuko says:
- "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."[3]
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.
For further information not yet integrated into the article, please see the series of forum posts starting here.