District of Flooded London.
The Drowned Tube. The flooded tunnel network under the city: EO research stations, salvage routes, and three sensor arrays calibrated to the relay's pressure points, running on a power source nobody has found. The Jubilee Line approach stays walkable on a low-current window. Station Alpha's surveys track new disturbance in the sediment; whoever moves down here is known within a session, though not yet by name. Cold. Bring your own air.
District 3. The flooded tunnel network under the city: EO research stations, salvage routes, the Green Coat Network's three sensor arrays, and the Jubilee Line approach that a low-current window keeps walkable. Cold.