You are correct!
From our dictionary:
in•su•per•a•ble
(in-sOO'pur-u-bul), —adj.
incapable of being passed over, overcome, or surmounted: an insuperable barrier.
(in-sOO'pur-u-bul), —adj.
incapable of being passed over, overcome, or surmounted: an insuperable barrier.
