'immense darkness' is correct and usable in written English.
You can use it to describe a situation with a deep absence of light or a deep feeling of sadness and helplessness. For example, "The night sky was filled with an immense darkness that felt like it was swallowing her up."
Manhattan's fabled night skyline flickers against an immense darkness in these photos.
The very last line of the book sees the Thames, not the Congo, seeming to lead "into the heart of an immense darkness".
"The offing was barred by a black bank of clouds, and the tranquil waterway leading to the uttermost ends of the earth flowed sombre under an overcast sky – seemed to lead into the heart of an immense darkness".
With the capital flowed the ships and steamers out of the Thames, sitting on board one of which was Joseph Conrad's traumatised Marlow, with his Congo tales of venturing "into the heart of an immense darkness".
What Smith grasps is "the immense darkness of the continent at whose edge the little city perched — from this one pinpoint of defiant flame, the thousands upon thousands of miles of night unrolling westwards".
"The offing was barred by a black bank of clouds, and the tranquil waterway leading to the uttermost ends of the earth flowed sombre under an overcast sky – seemed to lead into the heart of an immense darkness". Conrad's merciless short novel (fewer than 40,000 words) opens on the Thames and ends there, too.
Immense London darkness and stillness alone and deserted like a country place at night, just beyond the noises of the Euston Road.
However, underneath the glitter lies an immense blanket of darkness — these are the longtang of Shanghai.
He left behind him an immense city plunged into darkness, where the only lights were the reflections of his headlamps.
Other sculptures have the character of revelation, of ecstatic visions in darkness, of immense suffering silently endured, of what it is to be attacked.
But this study adds to a growing body of evidence that a range of creatures can cope with the near-freezing temperatures, immense pressures and complete darkness.
