In one implementation, a system for broadcasting on-duty adventure opportunities among computing devices includes an adventure management computer system to transmit (a) push notifications to selected mobile computing devices related to activated on-duty adventure opportunities and (b) local beacon signal identifiers for mobile-to-mobile beacon signal transmissions for the activated on-duty adventure opportunities, a guide mobile computing device to locally broadcast information for the on-duty adventure opportunity, and a participant mobile computing device (i) to detect the local beacon signals with the local beacon signal identifier for the on-duty adventure opportunity, (ii) to obtain the adventure information for the on-duty adventure opportunity from the adventure management computer system, and (iii) to reserve the on-duty adventure opportunity with the adventure management computer system.