From opening paragraphs:
This dungeon is located in and below a massive, ancient glacier, which is rumored to have swallowed a whole city in a time long
past. Each tale told of the city is different: some say the city was good, others evil, some believe the glacier that now buries the city was created to protect it, while others believe it was
meant to cage something in.
In your implementation, the secret buried beneath the glacier may not even be a city. It might be a buried temple, a long-lost tomb, an ancient white dragon's lair, or even a sacred spring that grants immortality. What lies beyond the map is left up to you.
Naturally other parties are interested in discovering what lies below the ice for various reasons. Intelligent humanoids are already at work digging through the glacier, and icy predators lurk in its frigid caverns. Even those who have perished while seeking the glacier's secret oppose the efforts of new adventurers.