The applications of ocean exploration lidars and underwater wireless laser communications put forward special requirements for the wavelength, repetition rate, and peak power of the laser source. The nanosecond pulsed blue-green laser with high peak power, especially blue laser with smaller attenuation coefficient in ocean water, is widely required for active oceanic remote sensing and high-speed information transmission. In this paper, the development status of blue pulsed lasers is reviewed, and the recent research on blue pulsed lasers emitting at the Fraunhofer line of 486.1 nm is introduced in detail from the perspective of two application scenarios, i.e., one with high repetition rate and multiple wavelengths and the other with high energy and high peak power.