Oceans are continuous waters that cover more than 70% of the earth's surface. The optical monitoring of marine life is very important for the protection of marine ecosystem. In this paper, a review on our recent work in the construction of compact hyperspectral spectrometers and lidar systems and their applications in e.g. marine biological detection was given. Hyperspectral imagers with different spatial scanning methods were demonstrated, which were used to detect several kinds of algae, zebrafish and other marine organisms under different modes, such as transmission, reflection and fluorescence modes. In addition, based on some machine learning algorithm, accurate classification of microalgae and accurate prediction of algae growth cycle were achieved. In the aspect of lidar, an inelastic hyperspectral Scheimpflug lidar system has been used to measure aquatic organisms in laboratory and inshore field environment and their fluorescence hyperspectra have been captured successfully, which demonstrated the great potential of the inelastic hyperspectral Scheimpflug lidar system in the application of marine biological monitoring. A four-dimensional detection system which could achieve high spectral resolution (3 nm), high spatial resolution and high depth precision (27.5 μm) was also presented.