I knew a young lady of the last "romantic" generation who after some years of an enigmatic passion for a gentleman, whom she might quite easily have married at any moment, invented insuperable obstacles to their union, and ended by throwing herself one stormy night into a rather deep and rapid river from a high bank, almost a precipice, and so perished, entirely to satisfy her own caprice, and to be like Shakespeare’s Ophelia.
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.