Star Ocean 3: Kirsla Mines, the Hauler on-rails maze section.
Can you believe it took me more than a YEAR just to get past the damn mines? Holy hell, the whole thing is a Guide dangit moment. You never know where the [tornado fang] you have to end, or at least i didnt. And you have those turtle things that each have their quirks. Im not sure why I never checked a FAQ to be honest. And even when i did, I was still frustrated by the damn place and it STILL took me a while, since it was right after a jump, like, jump and immediately slow down or something, and there were a few obstacles in the way that could do your hauler in if you werent careful.
On an inverse note:
I wouldnt mind repeating the Aquatic Gardens of Surferio bonus dungeon. That was kind of fun, and I especially liked the look and music.