I have begun a new mapping project for my face-to-face game of B/X D&D (played with some old friends and our kids). The Broken Bay lies to the east of the Axe Lands (land of small petty kingdoms "points of light in a harsh world"), the eastern lands are known as the Grey Wastes. Once a thriving land of enlightenment now a cold desolate realm covered in ash.
Ruins of once great cities dot the lands, and bands of mutants (humanoid races) haunt the landscape scraping to survive.
The islands in the Broken Bay are the Dread Peaks, once part of the range that was above the water here before the deluge in the age or ruins that cracked the land and the great sea flooded in.
This is all just conjecture for now...
The scale is 1 Hex = 10 leagues (or 30 miles).