Surely "endure" is an anagram of "under" (thence "divers" in biblical sense) + "e" base of natural...logarithms (Chambers), NOT "end" + "ure"?! That's how I u'stand it at least. Very tricky though!
i think you are right GK, i've heard of Euler's number before. Divers = diverse, i suppose?
the very mention of Chambers always puts me off - No can mean Yes.
did try to shoehorn Underwater RE.
Trevor & Chrise: much as I hated some of this puzzle at midnight, looking back I must admit that clues like 5d are actually pretty ingenious ---- completely misleading surface, perfectly OK when you eventually get there. I entered several just to get to bed, only to realize how they came together much, much later. Respect!