The Dan River is where most of the third Brotherband book, The Hunters , takes place. There are many cities down this river.
It is said that The Dan River's northernmost part is in the Stormwhite sea . (specifics are not written in the books)
The outlet, however, is close to both the Constant Sea and the Sea of Rostov . As said in book 3, page 320, "If Zavac left in the hours of darkness, they could lose him. . . He [Zavac] could slip away to the south, into the Constant Sea or the Sea of Rostov." Also suggesting that the city of Raguza is close to this outlet.