###### Abstract  
Underwater optical wireless communication (UOWC) is a field of research that has gained popularity with the development of unmanned underwater vehicle (UUV) technologies. Its utilization is crucial in offshore industries engaging in sustainable alternatives for food production and energy security. Although UOWC can meet the high data rate and low latency requirements of underwater video transmission for UUV operations, the links that enable such communication are affected by the inhomogeneous light attenuation and the presence of sunlight. Here, we present how the underwater spectral distribution of the light field can be modeled along the depths of eight stratified oceanic water types. We considered other established models, such as SPCTRL2, [PERSON]'s single parameter model for inherent optical properties, and a model for the estimation of the depth distribution of chlorophyll-\(a\), and present insights based on transmission wavelength for the maximum signal-to-noise ratio (SNR) under different optical link parameter combinations such as beam divergence and transmit power under \"daytime\" and \"nighttime\" conditions. The results seem to challenge the common notion that the blue-green spectrum is the most suitable for underwater optical communication. We highlight a unique relationship between the transmission wavelength for the optimal SNR and the link parameters and distance, which varies with depth depending on the type of oceanic water stratification. Our analyses further highlighted potential implications for solar discriminatory approaches and strategies for routing in cooperative optical wireless networks in the photic region. Underwater optical wireless communication; stratified waters; underwater sensor networks; mobile communication; solar noise; visible light wavelengths +
Footnote †: journal: Sensor and Actuator Networks  
submerged devices. For example, this may consist of a series of miniature biomimetic robots or a swarm of AUVs coordinating with solar-powered buoys and seabed-moored sensors to accomplish a mission [9; 10; 11; 12]. Flethers are the most common approach of communication between human operators and these underwater vehicles, termed collectively as unmanned underwater vehicles (UUVs). However, tethers limit UUV maneuverability and range due to drag, tension, and finite length, respectively, and are prone to entanglement and breakage, thus limiting the potential for swarmed operations [13; 14; 15; 8; 16]. Tethers are also subject to biofouling during long-term deployments. The alternative is to establish wireless forms of communication using acoustic, radiofrequency, optical, or electromagnetic links. Acoustic underwater communication, the most developed form, dates back to the late 1980s. Acoustic transmissions of image and control information over vast distances have been demonstrated since the late 1980s [17; 18]. However, they operate in the audible-ultrasound range (around 20 kHz), resulting in low bandwidths and data rates in the tens of kbps [19; 20]. Furthermore, although sound spreads outward as a mechanical wave with low directionality, it introduces challenges like reflections, multipaths, and channel saturation. The slow speed of sound in water of about 1500 m s\({}^{-1}\) is influenced by temperature, pressure, and salinity variations in the vertical channels (where link direction is vertical), and are further susceptible to ocean currents and Doppler effects causing delay spread and intersymbol interference (ISI) [21; 22]. Acoustic modems, though robust, are also cumbersome and costly, thus prompting the development of alternative solutions for wireless multimedia transmission for mobile underwater systems. Radiofrequencies (RF) may be more favorable candidates for underwater communication because these can achieve higher data rates, bandwidths, throughputs, and lower latencies.