The usefulness of maritime autonomous vehicles (MAVs) for military, commercial and other purposes will depend on where they can travel and what they can do en route. These activities, in turn, depend on how the international law of the sea regulates their navigation, including whether they will they be able to travel through the territorial waters of foreign states and the technology they will be able to deploy. This chapter argues the navigational rights through the territorial sea will be able to be exercised by MAVs without any real difficulty as the broad drafting of the relevant provisions of UNCLOS offer sufficient scope for their application to a wide range of MAV technology. Nevertheless, there are still some features of the regime that should be carefully considered by MAV designers and users. MAVs will have to be equipped with certain capacities, such as being able to turn off some of their sensors and information-collection systems and being able to travel on the surface. Most importantly, the design of MAVs should respect the legitimate interests of coastal states in being able to communicate with ships and vessels that travel through their territorial waters, or at the very least, to have information about how to contact the responsible person or organisation for clarification or complaint.