Undersea rhymes with:
forsee, oversea, ac, addressee, amc, apc, artsy, bbc, bresee, c, cc, cdc, cie, cxc, emcee, foresee, forsee, fsi, gassee, gnc, gutsy, hohensee, jaycee, jessee, keesee, kissee, knbc, lessee, licensee, losee, lxi, nic, ofc, oversea, pc, piercey, powerpc, sci, sea, see, si, sie, sieh, sightsee, tenn, tennessee, tootsie, tse, t_a_c, u_s_m_c, woodmansee, yangtze
Undersea sounds like:
under-age, underage, undercook, undergo, undergoes, underseas, underuse, undress