

I think there were actually three… One was that pocket dimension thing with the wormholes.
One was the area of space the Malon were dumping their toxic warp waste. The waste and radiation created an expanse of space that blocked the stars. And there was that native species that was being killed by the waste but had adapted to the darkness.
And then there was the section of space that was dark and many light-years across, again with some exotic radiation and most of the crew had to be put into stasis. Only the Doctor and Seven could be awake, but they started hallucinating like halfway through.
It’s been a while since I went through my last rewatch though, I could be mixing some stuff up or those last two might have been the same episode and I’m splitting it up from memory.
Strap a $20 Bluetooth speaker to the dash.