The underground tunnels of Marinburg can generally be divided into two areas: the Shallow City District and the Deep Mine District.
As previously mentioned, Marinburg's underground is composed of countless tunnel mines. Due to large-scale illegal excavation and construction, every house in the canal district and civilian district has a basement linking to the underground tunnels. Many smugglers use these tunnels to enter Marinburg, merchants establish warehouses and secret storage points underground, and even civilians unscrupulously build living areas in the tunnels.
But even so, humans have only utilized part of the underground tunnels. This part that humans utilize is the Shallow City District.
Marinburg's rulers have spent vast sums of money blocking and destroying parts of the tunnels and increasing personnel to guard some main tunnels, making the Shallow City District relatively safe.
The Deep Mine District is truly terrifying.
