If you're referring to a leisurely walk, especially one taken for pleasure:
* Rush
* Scurry
* Dash
* Hurried walk
* Run
If you're referring to a public walk or a place for walking:
* Secluded area
* Private path
* Isolated place
If you're referring to a formal, usually public, walk:
* Private gathering
* Informal gathering
It's important to consider the context to choose the most appropriate antonym.