During the last few years, the Internet of Underwater Things (IoUT) has become an interesting technology to discover unexplored underwater environments. IoUT enables scientists and researchers to remotely discover underwater phenomena and gather valuable information from the depths of the oceans using smart things. Due to the harshness of the underwater environment, collecting information with regard to QoS parameters and energy considerations is a major challenge. Software Defined Networking (SDN) is a centralized network management paradigm that helps to implement efficient routing approaches to provide QoS for network traffic flows. In this paper, we propose EQAFR as an energy-efficient routing schema by leveraging the capabilities of SDN to provide QoS for gathered underwater data which are sent from underwater things toward the sink. EQAFR is implemented in the SDN controller to gather the coordinate information and residual energy of things periodically. Then, it computes the delay and probability of data loss of the link and applies Fuzzy logic to compute the cost of links. Finally, it calculates optimal paths and installs the routes between the underwater things. Simulation results confirm that using EQAFR considerably improves QoS and prolongs the lifetime of underwater things.
