There's a hidden portal on the west coast of Bangkorai, I don't think it's intentional, but I could be wrong. Referring to the image below, if you travel south along the west coast from Evermore until you reach a pair of boats and some friendly fisherfolk, then try to travel around the headland that juts out to the west (and which is directly to the west of one of the wayshrines), you'll see the Stormhaven loading screen, and you'll find yourself back on the bridge between Stormhaven and Bangkorai, at the Stormhaven end.
I think it may be because that headland is right near part of the invisible border between the 2 zones, and trying to go around the headland (i.e. in the shallow water) results in you crossing the border.
This is repeatable, I've done it a few times before, just for laughs.

NOTE to moderators: I am only reporting an apparent glitch in the game, and have never at any time intended or tried to exploit this glitch for my own personal game gain. In fact, there's no apparent gain to be had from porting from this part of coastline to the inter-zone bridge, that I am aware of.
Edited by Beilin_Balreis_Colcan on May 5, 2022 11:57PM PC(Steam) / EU / play from Melbourne, Australia / avg ping 390