Professor Alto Barium left his unfinished findings on the ship ‘Mercator’. Split up in teams you will set out to solve the enigma of a mysterious map of Ostend. Different assignments and tests throughout the city centre will hold the key to success! The vessel Amandine, the wonderful fish stalls, the yacht club, the beach, the aquarium, the maritime museum … They each constitute an important step towards success. Who can decode the map? All partial codes have to be entered in the Astrolabe on the deck of the Mercator. A new element will be supplied each time. The team who cracks the code first will go home with a wonderful keepsake.