So your on a hunt to find juicy questions .... You click on the "unanswered tab"
Scroll down to the bottom and click on the very last tab (with 50 per page in this example) to get the "oldest"
Turns out that at least the last 250 + question in the unanswered tab all have answers. Which means that "unanswered" in this case probably means "sort unaccepted questions from zero answers to many answers". Understandable but not really what "unanswered" means and it makes it harder to service/find the oldest truly unanswered questions.
as pointed out in comments: There is a difference between ....
and ... which is what I was looking for.