'Multi-Domain Operations' paradigm has been receiving significant attention both in military and civilian worlds. This novel notion of operating networks of distributed and mostly unmanned autonomous devices in multiple domains-air, land, water, cyber, and space-in coordination to achieve a common objective, will undoubtedly be a key enabler for various applications. To realize this novel paradigm, it is imperative to establish robust communication links to transfer data between devices operating in multiple domains. However, as of today, establishing high data rate, robust, secure, and bi-directional communication links between aerial and underwater assets across the air-water interface is still an open problem. This article introduces the software-defined visible light networking to establish bi-directional wireless links through the air-water interface. We first overview the limitations of the state-of-The-Art solutions for communication across air-water mediums and alternative approaches. We then present a software-defined visible light communication (VLC) modem, which is the primary building block of our proposed solution. We also discuss the challenges, limitations, and opportunities of using visible light to communicate over the air-water interface. Last, we present some key concepts and applications that can be enabled by leveraging the proposed visible light networking solution. © 2018 IEEE.