A novel diterpene, laukarlaol, was isolated from the red alga Laurencia karlae Zhang et Xia, collected from the Nansha islands in the South China Sea. Its structure and relative stereochemistry was established by means of spectral data analysis. Complete 1H NMR data and assignment of the 13C NMR spectra are reported. Five known sesquiterpenoids were also isolated and identified as aplysistatin, palisadin A, palisadin B, 5-acetoxypalisadin B, and 12-hydroxypalisadin B.