The Sailor's Guild is an organization with a branch in "every port of every size", dedicated to the service and education of sailors. Vyse and his crew first encounter the Sailor's Guild on Sailor's Island.
The Guild seems to operate the way most historical guilds do, being run by people versed in the trade, and offers bounties for information on Landmarks as well as wanted persons.
It's there that Vyse can sell all of his discoveries and report the defeat of pirates on the Wanted List in exchange for Gold. Also, Vyse can sell Daccat's Coin at the Sailor's Guild in Nasrad.