Underwater optical wireless communications (UOWC) systems have recently received significant attention as an attractive solution for both research and commercial use because of their ability to provide high bandwidth communications over relatively short transmission spans along with their low operational cost. However, high absorption and scattering of optical transmission in the water limit the achievable range of underwater optical wireless links to only few metres. In this study, in an effort to increase the range and reliability of underwater optical wireless links, the authors propose to utilise semiconductor optical amplifiers at the receiver and discuss in a quantitative fashion the performance enhancements that can be achieved. After developing the required analytical framework, extensive numerical results are further provided to demonstrate the performance of the proposed scheme for different operating conditions. Specifically, assuming intensity modulation and direct detection schemes with on–off keying modulation, they evaluate the bit error rate of the proposed system configuration for different water types, link distances and forward error correction schemes. Performance evaluation results reveal that the use of optical amplification can significantly improve the quality of UWOC links.