Twelve feet.
3 seconds sound clip from the Ghostbusters II movie soundboard.
You can hear this line at 01:02:44 in the Blu-ray version of the movie.
Quote context
[...]
- Uh-huh. Did I tell you? I wasn't lying, was I?
- You know how much negative energy it must have taken to generate a flow this size?
- All right. Let's see how deep it is. Get a sounding.
- Hold on!
- Well, I'm trying to hold it.
- Give me a hand. Give me a hand!
- It's got ahold of him. Get his belt off!
- I can't hold it! Wait, wait, hold...
[...]