The Ship Graveyard is the 27th Discovery that Vyse can make.
This North Dannel route was once feared as the home of a monster that ate ships. But in reality, it is an area where currents are so strong that the previous generation of ships lacked the power and hull strength to make it through.
This is found inside the North Dannel sky rift, towards the middle. You can't get this until you obtain the Delphinus.