The Internet of Underwater Things (IoUT) is a collection of smart interconnected underwater devices to sense vast unexplored water areas. It is a worldwide network. The IoUT is the combination of internet, embedded sensors, and most efficient tracking technologies, which are utilized to sense and react to underwater environmental conditions.
   The IoUT devices are limited in resources like energy and computation. The characteristics of IoUT are diverse communication technologies, different tracking technologies, various energy harvesting models, dynamicity in network density, different localization models, and battery recharge complexity. The IoUT architecture comprises three types of layers that are perception, network, and application. The perception layer includes the objects used to sense and collect information.
   The network layer bridges the IoUV devices through wired or wireless internet-based protocols. The application layer consists of different intelligent solutions to efficiently meet the user requirements. Major applications of IoUV are aquariums, fish farms, pipeline monitoring, and harbor security.