The Mediterranean alcyonacean Alcyonium ( = Parerythropodium) coralloides (Pallas, 1766) is shown here to contain coralloidolide F ( = (+)‐(3a‐R*, 7R*, 8R*, 9R*, 12R*, 12aS*)‐8,9‐epoxy‐1,3a,6,7,8,9,10,11,12,12a‐decahydro‐3a‐hydroxy‐12‐isopropenyl‐2,5‐dimethyl‐1‐oxocyclopfintacycloundecene‐9,7‐carbolactone; (+)‐2), the first example of a 2,6‐cyclized cembranolide. Structural assignments are mainly based on ID and 2D NMR and MS data. Copyright © 1990 Verlag GmbH & Co. KGaA, Weinheim