How to play
The object
Each day you are shown one ship voyage. The port of departure is given; the port of arrival is hidden. From the shape of the track and the distance run, you have to work out where the ship went. You get six guesses.
Range and bearing
A wrong guess gives you two numbers. Range is the great-circle distance from the port you guessed to the real port of arrival, in kilometres, as the crow flies. Bearing is the true bearing between the same two points: 000° north, 090° east, 180° south, 270° west. So "4,200 km, 075°" means the answer lies 4,200 km east-north-east of the port you guessed.
The compass rose
The ring around the track is both frame and instrument. The bearing from each wrong guess is drawn onto that rose as a needle, and it stays there. Two needles give you a direction; three needles cross. This is the seaman's running fix — you establish a position by crossing several bearings.
Clues
Each wrong guess unlocks one clue in order: the type of ship, the cargo she carries, the straits the route transits, the arrival country and finally the first letter of the port of arrival. The strait clue is never written by hand — it is derived from the real geometry of the route. A ship running from South America to East Asia usually passes through the Sunda Strait rather than Malacca, and the clue says so.
The track
The track is real sea-route geometry: ships do not cross land, and they use the canals and straits. But there is no map. No coastline, no borders, no projection — only the shape of the route itself, fitted to its own scale. The sharp elbow of Suez, the wide sweep of the Cape of Good Hope, the short notch of Panama: the shapes are recognisable.
Rollover and streak
A new voyage opens every day at 00:00 UTC. A round in progress survives a page reload and carries on where you left it. Consecutive wins build your streak; missing or losing a day resets it. Voyages you play from the archive do not affect the streak.
Data
Port coordinates come from a hand-curated list built in the spirit of the World Port Index. Route geometry is generated with the searoute library. No live vessel tracking (AIS) is used; the voyages represent real commercial trade lanes, not a particular ship on a particular day.