Marine polycyclic ether natural products are known to be the secondary metabolites of unicellular algae, mainly dinoflagellates. This chapter provides an overview of the total synthesis of gambierol. The Sasaki/Tachibana group was the first to accomplish the total synthesis of gambierol. The Sasaki group successfully assembled the entire polycyclic ether framework of gambierol in a highly convergent manner. The Kadota/Yamamoto group relied on intramolecular alkylation of -acyloxy ethers and ring-closing metathesis (RCM) for the synthesis of polycyclic ethers. Subsequent RCM completes the synthesis of polycyclic ether XIV. The Kadota/Yamamoto group coupled the ABC- and FGH-ring fragments and completed the octacyclic skeleton of gambierol by exploiting their intramolecular alkylation/ RCM methodology. The RCM of olefinic esters proceeds via the intermediacy of titanium alkylidene complex, whose formation is a prerequisite for the productive RCM pathway. The gross structure and relative stereochemistry of gambierol were established through extensive 2D nuclear magnetic resonance spectroscopic analyses.