Muddy and murky waters lie under a bridge that seems to go nowhere. It is made of cobblestone and just as long as it is wide. Beneath it live a hideous troll that makes people pay to cross.
Troll's bridge, Swamp
troll
goblin
The goblin lives deep inside of caves far away from the sunlight. The goblin lives on deep cave algae and small critters and bugs that he can catch on the cave floor. The goblin avoids people as much as he can to stay alive.
Ah, what is that? What is what? Were you going to hurt me? What do you want from me? Only if you try and walk over my bridge without paying - I'm waiting to ransom this princess. Well, I have no use for a princess. Where did you get her?  The Castle over yonder - they were quite upset, but I gather I was rather unexpected.  Failed to make an appointment in advance you see. I have nothing. I can't pay you. I could help you in exchange for passage. Aye, we could make an arrangement.  These little ones in metal cans like to hide in little nooks and crannies.  If you can prod them out when they come, I'll let you eat half. Sounds right up my alley, Troll. What is she saying? Is someone coming?  Aye, about half a dozen cans coming this way, Clubby needs another workout! I'll get them!! This might be more your size little one, the club weighs more than you!