There are two docks at the same location. How do I get to both

Hint 1 of 12:

Experimenting will show you to go to the eastern one.

Hint 2 of 12:

You can't use the barge to get to both on the same play.

Hint 3 of 12:

If you fool around with the controls, you'll see how to get...

Hint 4 of 12:

...to the eastern one.

Hint 5 of 12:

Press the purple button so that you "go with the flow."

Hint 6 of 12:

How do you get to the western one, you say?

Hint 7 of 12:

Go to the catacombs first.