Underground resources are often addressed only out of necessity, leading to conflicts between uses and missing opportunities for productive synergies. The Deep City project is exploring a paradigm of ‘resources to needs’, which considers resource potentials prior to specific urban projects or plans. Mapping is central to the project and has been explored in several cities around the world. The ‘resources to needs’ paradigm, however, has received little theoretical or philosophical attention. To think resources before needs challenges common urban normative models and the process-oriented thinking of mechanical and ecological paradigms popular today. Where current methods for mapping the underground tend to enroll elements in a particular performance or resource use, Deep City seeks to facilitate an intermediate stage in which resource potentials can coexist without any pre-existing interaction or relationship. To think about the urban volume this way, this article works with the informational motor proposed by French philosopher Michel Serres. The logics of substitution and circulation of the map and its contents helps to think an alternative form of mapping in which the map itself becomes a reservoir of potentiality for thinking the urban volume less in terms of predefined functions and processes than a mass to be collectively cultivated.