The Deepsea Metro runs along ten lines, denoted by letters A to J, each containing stations that make up the Expansion's levels. There are a total of 85 stations, including eighty mission stations, four thang stations, and Central Station. 22 of the mission stations are exchange stations, connecting two different lines of the Metro. When Agent 8 completes an exchange station's mission for the first time, the connecting line is revealed and C.Q. Cumber gives them CQ Points as a reward.
With exchange stations having two numbers, one for each of the lines they connect to, the first number is always backwards alphabetically. For example, Girl Power Station is denoted J03D08 (and not D08J03) because J comes after D in the alphabet.
The mem cake for these stations is always from the series of the latter letter line as well.
The music played in the subway train has a few notes of the Calamari Inkantation played in the background.
More notes are added as Agent 8 gains access to more lines. After clearing the game, the complete track containing the main melody of the Calamari Inkantation is played.
According to a Famitsu interview,[1] Sound Director Minegishi comments that the Calamari Inkantation can be constructed as Agent 8's auditory hallucination, an inner melody of their mind that intensifies as more of their memory returns.
A poster advertisement of a video game console, resembling a Nintendo Entertainment System, can be seen in the subway train.
Deepsea Metro can be construed as a homonym of the D.C. Metro.
