I left the house, the horrid scene of the last night’s contention, and walked on the beach of the sea, which I almost regarded as an insuperable barrier between me and my fellow creatures; nay, a wish that such should prove the fact stole across me.
There are no more uses of "insuperable" in the book.
Show samples from other sources
This objection would be insuperable if Homer had been an Ithakan.
Homer -- The Odyssey
I came to the conclusion that difficulties, well-nigh insuperable, lay between me and the safe possession of the beautiful little vessel.