A window with the world map opens:
You have to move the map close to the solution position of the quest. Click on the map to center the map to this position. Use the interactors of the map to zoom and scroll the map.
Now move close to the Cape of Good Hope (if you are not sure, where it is - have a look at the About site).
When you are closed to the solution position, a pin is visible at the solution position.