Systems and methods for extracting and processing gases from submerged sources are disclosed. A system for removing and processing a gas from a submerged area in accordance with a particular embodiment includes a membrane or other open-bottom structure having a port and being disposed over at least a portion of the submerged area so as to at least partially enclose a volume of the gas. The system can further include a chemical reactor coupled to the open-bottom structure to receive the gas, and positioned to conduct a non-combustion reaction to dissociate a constituent from a donor substance of the gas.