Ocean scientific drilling is an important means of scientific exploration and research of the ocean floor, and has extremely important significance in many fields such as earth science, life science, and resource exploration. CORK (downhole long-term observation device) is an important supplement to ocean scientific drilling. Ocean scientific drilling mainly obtains core samples, while CORK focuses on long-term in-situ observation of drilled holes, which can fully utilize the drilling resources after drilling and achieve the transformation from short-term sampling to long-term dynamic observation of the seabed environment. Over the past few decades, the technological means of developing underwater observation equipment have also been continuously improved in this process. CORK has derived four new versions based on the initial development of CORK, which have evolved from single layer sampling to multiple layer sampling and can also perform in-situ testing. The new round of ocean drilling program led by our country is about to be implemented, and it is urgent to increase the research and development efforts of CORK technology, use our own resources and talents to build an underwater CORK observation system, and lay a solid foundation for quickly entering the ranks of world maritime powers.