While there isn't a single "official" dictionary definition for "hyperdeep," the term is used by geologists and enthusiasts to describe ultra-deep tectonic rifts or man-made boreholes that penetrate significantly further than standard structural cracks. These features are characterized by:

These cracks allow mantle heat to escape rapidly.

The phrase is often used as "flavor text" or lore in sci-fi settings (e.g., Warhammer 40,000 , No Man's Sky , or Minecraft mods) to describe: