The topic of ocean purification science fiction painting can choose to highlight the theme of ocean purification, such as a clear future or ocean redemption, in order to attract the audience's attention to marine environmental issues. At the same time, sci-fi elements can be added, such as the mission of future ocean purifiers or underwater robots, to increase the creativity and attraction of the works. Through this topic design, the audience can think about the importance of ocean purification and the potential of future science and technology while enjoying the works.