The waterfront is on the west side of Anselm's Landing, situated in a man-made inlet within the walls. A discreet inquiry with the harbormaster points you toward a large, deep-hulled vessel, and you make your way over to it.
Kurakana's ship is well guarded, and you can see a crowd up on the deck gathered around a red-robed figure whom you assume to be the merchant himself. A number of paper lanterns, hanging from wires strung between the masts, illuminate the scene. Kurakana seems to be celebrating. The ship clearly has a large cargo hold on and below the water level. If your tribespeople are still in Anselm's Landing, they're likely to be here, but if you're going to try to rescue them with a more subtle approach, you'll have to do so during the evening.