## 3 Marine Observatories  
An analog or digital transducer paired with a CPU and a communication interface is called a Smart Sensor. It is composed of a controller or processor that supports some intelligence, a transducer element, and an electrical signal conditioning system all combined into one package [36]. This type of sensor is known as a system-on-a-chip (SoC) because it combines electronics and a transducer (which changes form) element onto a single silicon chip. The primary goal of combining electronics and sensors is to create an integrated sensor, often known as a Smart Sensor. In the context of the Marine e-Data Observatory Network (MeDON) project (Figure 2), Smart Sensors should be employed in the project's development and deployment. Many advantages come from integrating a Smart Sensor into a MeDON project; here are a few of them: (1) The sensor's input is processed by the embedded CPU to produce meaningful information. This indicates that the device's Multiple Controller Unit (MCU) can compute the input data without using up all of its energy. By doing this, the device's power consumption from the base sensors is reduced. (2) The real-time data gathered by these sensors can be instantly linked to other devices and transferred via an Application Programming Interface (API) without the need for time-consuming intermediate processes. (3) It may receive input by recognizing different data parameters from several information sources and then utilize built-in routines to determine a particular combination of inputs before sending the data to networks that are currently active. (4) It makes it possible for information to be collected automatically, which reduces false noise that is recorded alongside accurate information. Consequently, a Smart Sensor can gather environmental data more precisely and with lower false noise [1]. In the context of Internet of Things (IoT) technologies (like MeDON), Sensors and Smart Sensors are essential components. Fundamentally, sensors aid in the gathering and processing of data used by IoT devices. In the IoT domain, a Smart sensor can then make certain decisions. Future big data collecting systems will be developed using Underwater Smart Sensor Networks with a focus on environmental data acquisition [13; 37; 38]. They enable the interchange and processing of data between the various devices (e.g., Smart Fusion Servers,Smart Sensors). We can install software components on all of these devices to handle and store the data and information. As long as the network is functioning properly, these components can provide new features or services such as the localization of marine mammals or underwater moving objects as the Marine e-Data Observatory Network (MeDON) project (Figure 2), which provides an example of a Marine Observatories (MOs). To provide such services, SSNs ought to consist of a network of specialized heterogeneous devices and communications infrastructure that can record and monitor data at different locations with varying levels of computational and communication capabilities with different communication protocols. In this situation, to provide such a localization service, the designer should be able to integrate N acoustic Smart Sensors (Smart Hydrophones) connected to Y Smart Fusion Servers to allow for data interchange between them. This exchange's scenario is predicated on the concept of Distributed Fusion Architecture (DFA) [10] (Figure 1). These servers process the acoustic data that the Smart Hydrophones collected before disseminating it over the network. The same database is used by all servers to store data to be analyzed to become information. The web server, where a web application is configured, receives the processed and analyzed data from the databases servers. As a result, the web server transmits, via a graphical user interface (Figure 2), the information picked up by the hydrophones, such as the voice of the dolphin, to the web clients. This implementation gives priority to modularity in its architecture.