The utilization of Free-Space Optical (FSO) communication in underwater environments is gaining momentum, particularly in Software Defined Underwater Wireless Sensor Networks(SDUWSNs). However, challenges such as high-energy loss and limited propagation distance persist in data transmission within SDUWSNs. In addressing these issues, this study introduces an innovative approach known as Software Defined Free Space Optical Underwater Wireless Sensor Networks, where FSO communication is seamlessly integrated with SDUWSNs to enhance network longevity. To optimize the performance of SD-FSO-UWSNs, the implementation of clustering and routing is explored as an effective strategy for energy-efficient data delivery. Nevertheless, the selection of optimal control nodes (CNs) in clustering poses a significant challenge. In response, a novel self-adaptive cheetah optimization-based clustering approach (SACO-CA) is proposed by incorporating self-adaptive inertia weights to identify optimal CNs based on a devised fitness value. The fitness function considers important parameters such as energy levels and distances among network devices, aiming to balance cluster sizes effectively. Moreover, the NS3 simulator is used to run network simulation while, SDN policies are implemented through the Open Network Oper-ating System (ONOS) controller. The simulation result metrics, including stability period,alive nodes, average residual energy, packets transmitted to the control server, and averagedelay, indicate that SACO-CA outperforms existing state-of-the-art methods. The results underscore the efficacy of the nature-inspired SACO-CA approach in optimizing CNs and improving overall network performance in SD-FSO-UWSNs.