The Sea of Coin lies between Feldia in the north and Kretavia in the south, and it carries more cargo than every road in the charted world put together. It is deep, well charted and heavily sailed. It is also the place where two nations that dislike each other are obliged to meet several thousand times a year, which is the other half of its character.
The water
Big vessels can work it. The soundings are good, the coasts are surveyed, and a competent master can cross from the Feldian shore to Sahalim in under a fortnight in decent weather. Decent weather is seasonal. From late autumn the gales come through in trains, the winter sea is genuinely dangerous, and by midwinter most of the trade is sitting in port waiting. The season opens again in spring, and the first convoy out of a harbor is an occasion in both countries.
Two island groups sit at either end. The Bagii Isles lie at the western end off the Feldian coast; the Bagii Atoll lies at the eastern end off Kretavia. The same people hold both and move between them, and together the two form a bridge across the sea for anyone willing to sail the long way. Bagii pilots are the best in these waters, and are hired as much for their weather sense as their charts — including, they will tell you, for reading where the krakens are running, which northern captains repeat with a straight face because the pilots are usually right about something.
The canal
The single deep-water passage between the Sea of Coin and the northern waters runs through Seehaven territory. There is no alternative for a loaded hull. Seehaven takes a toll, requires a manifest, supplies a pilot whether one is wanted or not, and has grown rich and unpopular on the arrangement.
Kretavia depends on that passage for access to northern goods and resents depending on it. Kretavic raiding along the Seehaven coast is regular and destructive, and while some of it is straightforward piracy, nobody in either country believes that is all of it. A raid is also a demonstration: the passage could be closed. Seehaven has responded by becoming permanently hostile to anything sailing up from the south, which affects honest southern traders considerably more than it affects the raiders.
The crossing routes
Most cargo goes by the short reach, the direct crossing through the canal — fastest, tolled, and carrying the risk of meeting a Kretavic hull in open water. The alternative is the Bagii crossing, island to island across the middle of the sea, which adds weeks and avoids Seehaven and its politics entirely. Some shippers pay the premium as a matter of policy. Northern hulls on the short reach cross in company through the raiding season, usually behind a hired escort, and underwriters in Kronstadt price a lone sail accordingly.
What crosses
North to south: grain from Kornfeld, wine from Kronstadt, furs and timber from Waldheim, iron from Steinmark, salt and salt fish from Seehaven. South to north: spices, oil, dates, fine metalwork and textiles, and materials with no northern equivalent that arrive without much explanation of where they were dug or grown.
Settlement is in weighed silver more often than in stamped coin. Neither nation trusts the other’s mint, both trust a balance, and every substantial market on either shore keeps a counting bench and a sworn weigher whose word ends the matter.
What merchants are talking about
Traffic in iron and finished weapons has risen sharply over the past two years. The cargoes are real and the manifests are in order; what is unusual is how much of it moves through intermediaries, with the buyer named as a broker’s house and payment settled by instruments that pass through three cities before anyone sees metal. Insurance rates on iron have moved in a way that does not match the risk at sea.
Merchants notice this sort of thing. They have not agreed on what it means, and they are watching the traffic between Kretavia and Eisenmark with particular attention.