The important thing here is to show how your intrusion interacts with a variety of things.
Ideally, choose things that are party of a single class.
Dickens followed his fog through all different types of boats. What could you do?
(In our Brisbane example, we'll follow the sweat around different types of dwelling (timber houses, apartment buildings, and tents). In our Tampa example, we'll follow the gators around different types of water source.)
If you can, try to choose things that mark different points along an imaginary axis. Dickens chose boats of different sizes. What could you do?
Try find some vivid verbs to express the action of your intrusion.