"OK." It seems the merfolk don't have much useful information about the pirates. If this is the case, then a generic advance seems their only option.
After dark, the 7 intrepid adventurers, Jack, Iggy, Planus, Charlarn, Opale, Ducane and Zach climb aboard their rowboat. The stronger members take the oars, and they set out towards the island, trying not to make too much noise, and bearing no lights.