Born in the abyssal trenches of the primordial ocean before continents fully formed, the Fathomless Cadborosaurus has traversed the world's evolving waterways for millions of years, witnessing the emergence and evolution of all cryptid species. As landmasses shifted and separated, this ancient sea serpent maintained connections between isolated cryptid populations through subterranean rivers and oceanic migrations, its various appearances across cultures spawning numerous serpentine legends while maintaining its true Cadborosaurus identity.

The Fathomless Cadborosaurus possesses a remarkable amphibious physiology that allows it to navigate both oceanic depths and freshwater systems, enabling it to appear in lakes, rivers, and seas worldwide through hidden aquatic networks. Its serpentine body can grow to immense lengths exceeding 70 feet when fully mature, with specialized gills that extract oxygen from water of any salinity and lungs that allow brief terrestrial movements. The creature's most extraordinary ability lies in its biofluorescent scales that absorb and store cryptozoological energy, allowing it to sense the presence of other cryptids across vast distances and occasionally manifest aspects of their forms while maintaining its core Cadborosaurus identity.

The Fathomless Cadborosaurus serves as the silent chronicler of cryptid history, maintaining the delicate balance between concealment and revelation that has allowed cryptid species to survive alongside humanity throughout the ages. It occasionally guides worthy cryptozoologists toward significant discoveries, strategically revealing itself to maintain humanity's belief in the unknown while ensuring that the most sacred cryptid sanctuaries remain hidden from exploitation.