This paper presents the design and construction of Guanay-II vehicle. It is an autonomous underwater vehicle that navigates over the sea surface and, at certain fixed points, dives vertically to obtain a profile of a water column. It was designed for shallow water, with maximum depth of 30 m. The vehicle uses a cylinder to do the immersions. The cylinder can take in and eject water smoothly, thus it can change the vehicle’s buoyancy, and avoid creating perturbations in the environment. The designed vehicle has a double-hull structure. The external fiberglass hull, which is not watertight, has been designed in accordance with Myring profiles to provide good hydrodynamic performance. The watertight module located inside the external hull is made of aluminum and contains the immersion actuator, batteries and the electronic system to control the vehicle operations. The control system is divided into several subsystems: navigation, propulsion/immersion, safety, communication and data acquisition. The vehicle is 2300 mm in length by 320 mm in diameter, and weighs 90 kg.