A wide variety of marine organisms--the majority originating from the ocean off the coast of California and the rest from the Indian and Pacific Oceans--are being examined for the occurrence of novel natural products with major emphasis on steroids and terpenoids. Separation techniques employed are primarily gas chromatography (analytical as well as preparative) and high pressure liquid chromatography, while mass spectrometry (both light and low resolution) and nuclear magnetic resonance spectrometry (both proton and carbon C-13) are two of the principal physical methods used in the structure elucidation work. Synthetic studies center on methods for generating stereospecifically some of the novel side chains (e.g., cyclopropane-containing) which are encountered in marine sterols.