Ocean optical systems have played an increasingly important role in ocean exploration, development and monitoring. Underwater wireless optical communication and underwater lidar are two types of ocean optical systems that are rapidly developing and have good application prospects. Underwater wireless optical communication is an ideal communication option for short and medium range applications due to high speed and low latency. Underwater lidar is also a highly precise and efficient observation method in applications like deriving geographic information and target detection. However, the complex optical characteristics of seawater channels have brought challenges to the further improvement of the performance of ocean optical systems. In seawater channels, not only strong absorption and scattering, but also dynamic interference factors such as turbulence and bubbles exist in the channel. In order to deal with these challenges, on one hand, signal to noise ratio can be increased with temporal or spatial methods. On the other hand, the conversion between temporal and spatial domains is beneficial to achieving better system performance. This article reviews solutions above and the development trend of ocean optical systems is pointed out.