Supernato, supérnatas, pen. cor. supernatâre. Plin. To swimme vpon.
Lewis and Short: Latin dictionary
sŭper-năto, āre, v. n., to swim above or on top, to float (post-Aug.), Col. 12, 9, 2; Plin. 7, 15, 13, 65; 28, 9, 35, 134; App. M. 6, p. 180, 36; Paul. Nol. Carm. 21, 179.— With dat.: arieti (Phryxum), App. M. 6, p. 185, 33.