This paper investigated the deployment of Optical Wireless Internet of Things (OWIoT) systems within underwater environments, addressing the significant challenges faced by RF communication, including signal attenuation and interference. The advantages of optical wireless communication, such as higher bandwidth and enhanced security, were highlighted as particularly suitable for aquatic conditions. Through simulations conducted using Ansys Zemax software, LEDs operating at a 625 nm wavelength were identified as optimal, demonstrating a potential frequency bandwidth of 10.52 MHz at a bias current of 150 mA. This configuration was found to optimize signal integrity and extend communication range underwater. Subsequent experimental validation confirmed the simulated performance, with consistent data transmission over a 1000 mm underwater path and minimal signal degradation being achieved. The integration of simulation insights with empirical evidence was shown to solidify the foundation for advancing OWIoT technologies, offering a robust solution for underwater data communication and marking a significant advancement in overcoming the barriers of underwater IoT deployments.