Originally posted by Czeresiowskill:

I was sure the mistlands introduced this tree.

Nope.

Originally posted by Czeresiowskill:

And you have to enter it.

Nope.

Originally posted by Czeresiowskill:

But the further I swim, the more I'm sure it's a texture from the beginning of the game....

Yip.

Head out to roughly between 2/3 to 3/4 from the centre of the world. If you sail passed a bunch of black rocks sticking out of the sea and/or see a tonne of thick impenetrable mist (not the super thick fog weather) - that's the mistlands.