Four new diterpenes named tagalons A-D (1-4), comprising an isopimarane (1), two 16-nor-pimaranes (2-3), and a dolabrane (4), were isolated from the Chinese mangrove, Ceriops tagal, together with four known dolabranes containing a 4,18-epoxy group, viz. tagalene I (5), 4-epitagalene I (6), tagalsin