Autonomous Underwater Vehicles (AUVs) are machines designed to operate underwater without direct pilot control and are untethered, allowing them to navigate freely over long distances according to a pre-defined operational plan, distinguishing them from Remotely Operated Vehicles (ROVs). They are used in a range of operations, including: • Seabed mapping • Underwater infrastructure location and monitoring • Wreck location and survey • Oceanographic conditions and underwater ecosystem studies. • Environmental monitoring (water quality, contaminant detection,emperature variations, etc.). • Security applications such as mine detection and monitoring of sensitive areas Like ROVs, these machines can be classified according to their payload, the tasks they can perform, and the operating depths at which they can operate. Many are multi-ton machines designed to operate for long periods of time, requiring them to be deployed from adequate surface supports, limiting their use to specialized companies, and operations with significant financial support. However, advances in miniaturization and the reduction of the cost of electronic components and batteries have allowed manufacturers to develop ranges of light machines that are more affordable in terms of purchase and operating costs, making them suitable for operations with smaller budgets and allowing the companies that employ them to be better prepared for the operations they are contracted to perform. This category of machines is designed to be easily carried by one or two people, which, in addition to their more reduced cost, gives them the following advantages: • Their limited weight and size make them easy to transport and deploy, even in remote or hard-to-reach locations. • In addition to the above, they can be deployed and recovered using small, non-specialized surface supports. • Also related to above, they require smaller teams to operate than large machines. • Depending on the model, they can be utilized for specific tasks similar to those assigned to larger units. • They have a smaller footprint than several-tonne vehicles, making them suitable for operations in confined spaces or ecologically sensitive areas. Like all tools, these machines have limitations, mostly related to their small size: • They offer limited internal space for sensors and other equipment, which restricts their functionality compared to larger machines. • Their small size also results in smaller batteries, which, despite their motors' more reduced energy consumption, often result in shorter operational durations due to the limited battery capacity. • They may be unable to operate at very deep depths due to structural limitations. • Their limited on-board power reserve may necessitate more frequent recovery and launching. More frequent data offloading and external processing may also be required for the same reasons. • The limited power of small motors in some of these machines makes them more susceptible to currents and other environmental factors than larger, typically more powerful machines, which can affect their operational capabilities. Despite their limitations, the advantages offered by these machines make them a complement to larger machines and allow small companies to enter new markets, in addition to the advantage they provide by enabling teams to study a site before starting operations and organize according to what is discovered, which can substantially save time and money, considering the operating price of a DSV. The following list provides an overview of the types of machines manufacturers offer. Of course, it must be kept in mind that the market offer is not limited to this list, as these manufacturers and their competitors constantly improve their offerings. Please note that the machines are classified from the lighter to the heavier models.