Doomsday Equation: Countdown to the Deep Sea in 385 Days

This is a story that takes place in the deep sea - for the people in the book, the ocean is the sky, and the sea surface is a forbidden area that can never be touched. A low-level scribe who has been hiding for more than ten years, a violent mechanic who is despised by the academic world, embarks on a retrograde journey to the "sky" with an ancient intelligent brain of unknown origin and evolution. Does the equation have a solution? If there is no solution, how to choose?