Dead end in a fifth market when looking for a route to the fourth market away from the shore.

I have found more mazed territories when looking for a route to the fourth market that does not force me along the sea.  I do not find one, but I do find a dead end with a fiftmarket in it. This time again with a candle and a key, like the first.  Keys have been needful in the underground temples. Perhaps there is one near by?

I explore south, but in trying to determine if the flames of the blue candle works on foes above ground as well, I burn away the remainder of my health and perish.