I highly recommend Blue Planet 2, which is really excellent. I, a person who doesn't like documentaries, fell in love with them. During the four-year shooting process, the shooting team * * * made 125 expeditions, and the underwater shooting time alone exceeded 6,000 hours. Compared with Blue Planet 16 years ago, the production team overcame various technical problems and limitations through new technologies, and presented many unknown fields and biological actions in the past to the audience perfectly.