And how do I find THIS place?

Hint 1 of 11:

Frog Rock is pretty nondescript.  It doesn't advertise much because there's
not much to advertise.  You won't find any souvenirs to lead you to it.

Hint 2 of 11:

There are two pretty reliable ways to find tourist traps.  What's the other
one?

Hint 3 of 11:

Since you're not going to find a souvenir, you need to find someone who will
tell you about Frog Rock (and also why you want to go there).

Hint 4 of 11:

Somebody close to bigfoots.

Hint 5 of 11:

Talk to Dougie's uncle, Shuv-Oohl.  If you can't find him, read the next
clue.

Hint 6 of 11:

Shuv-Oohl is behind one of the doors at the Mystery Vortex. (If you can't
open the doors, go to the Mystery Vortex hints.)  Shuv-Oohl will tell you HOW
to find Frog Rock, but it won't appear on your map YET.  That's right, this
is a two-part puzzle--you'll have to do something else as well to find Frog
Rock.