The first two dangers the narrator faces would be the pit and the pendulum (the story is aptly named). Because the room he is trapped in has no light at all, he stumbles around in the dark, feeling his way along the room, until he falls face-first to the ground. When he is lying down on the floor, he notices that his forehead and nose, though his face is angled down, are not touching anything. That is when he realizes that there is a pit in the room, which he tests the depth of by throwing a piece of the ledge into it. Next is the pendulum, with its ever lower swings, threatening a slow and agonizing death. He does face other minor problems, such as the drugged water and the rats eating his only food, but I would not consider those true dangers.
After being drugged by the water, the narrator passes out, and when he wakes up, he finds that he has been bound to a platform of wood by a strap that encircled his body and limbs, save his left arm from the elbow down and his head. He struggles to release himself, but in the end, he only manages to escape by rubbing his remaining food on his bandages and falling still so that the rats come and chew straight through them.
The first danger the narrator faces is being in an unfamiliar room in the dark. He makes his way around the room and finds there is a pit into which he could fall. The second danger he finds is the bread, which he devours and then realizes has been laced with some sort of drug or poison.
When he wakes up, he is tied to a bed or platform of sorts and the razor-sharp pendulum is descending upon him. He takes the salty meat that was left for him (no water) and smears it across his ropes. The rats that live down in the pit smell the meat and then chew the ropes, which frees the narrator.