From the air they look like the latter.
|Watersheds in most other parts are dry land.|
Not in the south Florida:
The watershed is the water way
But on the ground in the middle of one looking up there is no mistake.
As for the Everglades ridge and slough, the two look distinctive from one another in the air (i.e. sloughs are the open water channels and the ridges are the green space between.) But on the ground it's a whole different story. Where slough ends and ridge begins is tricky to discern.
The jury is still out if you must get closer or farther a way to clarify the view.