Abstract: Marine cabled seafloor observatories have been constructed and developed quickly recently in the world. Based on scientific requirements and objectives, many countries, including Canada, United States of America, Japan, and European countries, have built up cabled seafloor observatories, respectively. Infrastructures and progresses of different cabled seafloor observatories constructed by different countries were outlined and reviewed in this paper. Since 1978, 10 cabled seafloor observatories in Japan have been successfully built using coaxial cables at the beginning and using fiber-optical cables recently. One near-coast seafloor observatory and one regional-scale observatory were built in Canada. Two seafloor observatories were organized and managed by the Ocean Network Canada (ONC), and both are maintained by the University of Victoria. In 2012, the longest regional cabled seafloor observatory in the world (nearly 900 km long) was deployed in the USA. Cabled seafloor observatories in Europe have been planned to cover different ocean regions. In China, cabled seafloor observatories were built in Taiwan (MACHO) and in the East China Sea (Xiaoqushan). Based on these cabled seafloor observatories in the world, we proposed important technologies required by ocean networks, and suggested that remotely operated vehicles play key roles when cabled seafloor observatories are reconstructed. Finally, the development and challenge of cabled seafloor observatories are discussed, including some key notes and questions that should be considered by decision-makers when a new cabled seafloor observatory will be prepared and developed in China.

Key words: marine cabled seafloor observatory, seafloor fiber-optical cable, remotely operated vehicle, scientific node, junction box