Supporting Vasha in his adventures in the Ghost Archipelago, is the Earth Warden, Covis. For Covis’s four spells, I chose Projectile, for offensive punch; Earthen Wall, to cut lines of sight; Earth Blood, to aid everyone in the warband; and the Water Warden spell, Amphibious, because, well, there is a lot of water around…
Water plays a large role in Ghost Archipelago and is chiefly encountered through two rules, swimming and small boats. Swimming comes into play any time a figure activates while in deep water. That figure must immediately make a Will Roll, with penalties for wearing armour or carrying shields or treasure. If the role is failed, the figure receives no actions and will take drowning damage. Otherwise, he can activate as normal, swimming around and fighting with penalties. Of course, if the figure is somehow amphibious, it does not need to make the roll nor does it suffers any penalties.
Now, most Ghost Archipelago scenarios are set completely on land, but there are a few that involve deep water. In these scenarios, the players are often given the option of putting their figures into small boats. These boats can generally hold up to 6 figures, and have their own rules for movement and fighting. So, while larger ships are handled in the abstract, these smaller boats are on the table in the fights!
None of these rules are revolutionary or overly complex, but I think they go a long way to help giving the game some of its feel and to separate it from Frostgrave.