A novel compound zoanone A (1), together with eight new alkaloids, 3β,14α-dihydroxy-28-deoxyzoanthenamine (2), 7α-hydroxy-28-deoxyzoanthenamine (3), 3α-hydroxyzoanthenamine (4), 7β-hydroxyzoanthenamine (5), 28α-methoxyzoanthenamine (6), 28α-methoxykuroshine A (7), 30-hydroxykuroshine A (8), and 3β-hydroxy-11-deketo-kuroshine B (9), was isolated from the zoantharian Zoanthus vietnamensis. Their structures were elucidated by the comprehensive analyses of IR, mass spectrometry, NMR, and UV spectroscopic data. The absolute configuration of 1 was established by single-crystal X-ray crystallographic analysis using Cu Kα radiation. A plausible biosynthetic pathway of 1 was proposed. Antiangiogenic and antilymphangiogenic activities of the isolated metabolites were tested and evaluated. The results showed that all isolated compounds had weak antimetastatic activity.