The objective of this lecture is to provide insight specific to deep-sea underwater vehicles and their operation. It gives an overview of existing underwater vehicles, observatories and operations procedures, with emphasis on the Underwater Systems developed and operated within the French Oceanographic Fleet. Sensors and equipment required for deep water submarine operations will be presented. A focus on acoustic communication necessary for the operation of AUVs (Autonomous Underwater Vehicles) will be carried out in terms of principle, strategies and equipment. Instrumental architecture and key principles of distributed multi-sensor acquisition systems will be exposed. Visual perception in deep-sea operations as well as 3D representation of natural structures on the ocean floor will also be deepened