Range–only navigation – maximizing system observability by using extremum seeking∗∗This work is supported by the European Commission under the FP7—ICT project “CADDY – Cognitive Autonomous Diving Buddy” under Grant Agreement No. 611373 and by Office of Naval Research Global under grant N62909-14-1-N076 (DINARO). Filip Mandić is financed by the Croatian Science Foundation through the Project for the young researcher career development.