An Evaluation of Deep Water Navigation Systems for Autonomous Underwater Vehicles * *This work has been supported by the NATO Allied Command Transformation (ACT), under the Collaborative Anti-Submarine Warfare Programme (CASW), by the Office of Naval Research Global under grant no. N62909-16-1-2095, and by the Collaborative Localisation and Navigation of Autonomous Underwater Vehicles (COOLAUV) Agreement between NATO STO CMRE and Università di Pisa (ISME node).