The open-water marvels are called "polynya" in modern Arctic books. Polynyas are areas that remain ice free, or nearly so throughout the winter. (Mowat, 1998/2000)
Today satellite photographs clearly show the open-water marvels in Ungava Bay.
Comment:The primary conditions for some polynyas appear to be a high tidal surge, a narrowing of the main flow channel, and a shallow sea floor before the water reaches shore.