“…It can be found that most of the efforts are related to general ocean sensing and monitoring [ 4 , 23 , 40 , 44 , 46 , 47 , 50 , 53 , 55 – 57 ] and water quality monitoring [ 39 , 42 , 43 , 49 , 51 , 54 , 58 ]. Some specific efforts have been made for fish farm monitoring [ 45 , 48 ], coral reef monitoring [ 41 ], and marine shellfish monitoring [ 52 ]. Some projects focus specific technologies or devices, e.g., buoys [ 23 , 40 , 53 , 57 , 59 ] which will be further discussed in Section 4.2, and energy saving and harvesting [ 4 , 43 , 48 , 50 , 52 , 56 – 59 ], discussed in details in Section 4.3.…”