Travel in the Swamp

The trek through the swamp is an arduous one, and should offer many chances for random encounters along the lines of the those mentioned in the previous post. I'm not conveying the sense I want with this. I can't seem to get it to fit the image in my head.
I wanted this to be a difficult landscape to pass through, dark and close, danger at every step. Narrow pathways, uncertain direction, hazards everywhere. Dead ends, false turns, and all that kind of thing. What I see here is something too open and broad. It doesn't feel right. I wanted a nearly impenetrable location with a village cluster at its heart. There needs to be a hard-won passage to the village, a confrontation with the slaad at its heart, and then an escape through uncharted swamp to the back entry into the lair.
I think it needs to get darker and more difficult as it progresses. But how do you have lava flows and make them passable? I'm not sure.
I guess that getting closer to the peak can mean fog and mists. I think sinkholes and a mix of tunnels and cracks can help. But none of that plays up the swamp element. This approach to the mountain is meant to be "unguarded" in the sense that the natural terrain discourages it. The map is an invitation to try, and a chance to succeed. I want the whole area to be a brackish, oozing quagmire, flowing down a difficult slope.