When I put together a prompt, I break it up into three steps. The first relates to style and form: photorealistic, perfect anatomy, detailed face, detailed hair, detailed eyes. With NovelAI at least, the more tags you put, the more the image will focus on them (e.g. "detailed face" will tend to force headshots)
I would also be using lighting, angle and framing tags here if I was using them. I also have a lot of negative prompts (lowres, text, error, worst quality, low quality, jpeg artifacts, ugly, duplicate, morbid, mutilated, out of frame, extra fingers, etc.).
The second is the environment. Because AI doesn't have a concept of "quicksand" the way we do, I blend in a lot of similar textures and descriptors: quicksand, squishy mud, soft mud, deep mud, girl sinking in quicksand, partially submerged in mud, girl sinking in mud, girl trapped in mud, struggling in mud, etc. Add in textures like "ripples" or swap things out like "sand" to get a closer approximation, plus negative prompts like "water" and "reflections" to reduce the watery appearance. Then the appropriate background (jungle, forest, swamp, construction site, etc.). I like to do in-painting for these to give the AI more direction in what I'm envisioning - most of the ripple effects are prompted by my squiggles.
Third is the subject itself, which is normally the descriptor for the character: woman/girl, brown hair, worried, scared, open mouth, parted lips, wide eyes, yellow waterproof jacket, etc.
Without any in-painting, that combination gets me results like these.
jacket4.png
jacket5.png
yellow4.png
yellow3.png
I'm not familiar with how Midjourney works. My advice in creating prompts is not to rely heavily on prose. Things like "mired in peat" or "stuck in marsh" are, in a sense, both too broad and too narrow. Most of the entry-level AI tutorials I've seen get people to use prose to begin generating abstract concepts, but you learn quickly that it's hard to get exactly what you want from these requests alone.