This happened a couple of months ago. I had what felt like a mixture of a dream and astral projection. (I hope this is the right category.)
I could feel myself lying down in bed. My attention was drawn to the side of my bed and I could hear a shuffling. I then saw a black orb and felt a weight as it landed on my chest. It then felt as if I descended through my bed and was suddenly dunked into water. My vision faded and everything around me went black.
The black orb changed into the figure of my demon companion. I could feel him holding me in his arms as we went deeper into the water. I started to panic because I could see him, but I couldn’t see my surroundings. He told me we were in, “the abyss.” I made a comment, “I can’t see anything.” I remember him chuckling and saying, “Well I can.” I watched as he shifted his form, his eyes fading away. I got a feeling that other senses would be more important there, but I couldn’t let go and relax enough to focus. I then reacted like a person who was drowning, grabbing onto him and trying my best to get back up. He released me and I ended up astral projecting a second time that night without intending to do so. I could not feel his presence this time.
I got an image of myself being stuck in a narrow burrow. A large reddish squid creature was guarding it. I got the sense it had trapped me and wanted to eat me. My patron saved me this time. Picking me up and safely returning me to the surface.
I’m still curious about what happened there. I couldn’t see the first time, but when I was alone and should have been more frightened I was able to see what was going on. It makes me wonder if it was some sort of lesson. 
I had no intentions of traveling to the abyss either and it hadn’t really crossed my mind to do so before that night.
Lately I’ve been getting the feeling I need to return to this realm. I think there was something I was unable to see or fully learn last time I was there.