In Blackbeard's time, the river flowed this way, and the inn wasn't on the island at all, it was part of the mainland.
9 seconds sound clip from the Blackbeard's Ghost (1968) movie soundboard.
You can hear this line at 00:17:21 in the Blu-ray version of the movie.
Quote context
[...]
- Fine. Much better than we'd expected. Thank you.
- That's good. No problem, then?
- We still have another $38,000 to give Mr. Seymour before the first of the month.
- Why is Seymour so anxious to get his hands on this property, anyway?
- Here, I'll show you on the map. You see, this is the island we're on.
- As a result, nobody's ever been able to clarify what the legal jurisdiction of the island really is.
- That's where Mr. Seymour comes in?
- Sure. He can tear down the inn, put up a big, modern casino, and the law can't bother him.
- Oh, uh... Well, I'd like to thank you for what you did tonight.
[...]