The world of The Water Road is dominated by the continent of Altreria. It’s where the titular river is, where the Neldathi and Triumvirate face off, and where most of the action in the trilogy happens. It’s not the only bit of real estate in this world, however.
The Slaisal Islands are a chain of islands that lie off the continent’s northeast corner, curving away from the Badlands toward the northeast. Those who live there, called Islanders, are, naturally enough, sailors and fishers. In general, they stay out of the political squabble between the Triumvirate and the Neldathi. In short, if there’s a vacation spot in the world of The Water Road, this is it. I mean, consider the sunsets:

Not really the Slaisal Islands, obviously – they don’t even have cameras yet! But you get the idea. Photo of Lake Malawi in Tanzania, courtesy of Wikimedia Commons.
The Islanders are also traders, effectively controlling the commercial network at sea. Since they’re not part of the Triumvirate they aren’t bound by the alliance’s command to not do business with the Neldathi. In fact, there are four Islander cities along the Neldathi coast. They serve as way stations for Islander vessels, but also provide the only regular contact between the Neldathi and the outside world. There’s a similar Islander city on the northern coast, serving the same function with the Azkiri nomads who roam the Badlands.
In spite of their position on the periphery of events in Altreria, the Islanders are a key part of the story of The Water Road.