Giant oil and gas fields in the southern part of Mexico and out through the Yucatan area are discussed. "South Zone" exploration (as defined by the exploration program of Petroleos Mexicanos) includes production areas in the Mexican states of Guerrero (southern part), Oaxaca (southern part), Chiapas, Quintana Roo, Yucatan, Campeche, Tabasco, and Veracruz (southern part), and includes some areas offshore Mexico in the Gulf of Mexico.

A history of exploration and production is highlighted since 1938 (nationalization), and stratigraphy, structure, and accumulation of petroleum of giant fields are described.

Fields in the Isthmus Saline basin which are included here are: Tonala-El Burro, El Plan, Cinco Presidentes, Magallanes, and Ogarrio. Fields in the Macuspana basin include: Jose Colomo, Chilapilla, and Hormiguero. Sections of the manuscript also discuss the generalities and stratigraphy of the Chiapas-Tabasco Mesozoic Area (including the Sitio Grande field, Cactus field, and the Antonio J. Bermudez complex), and the general stratigraphy and hydrocarbon accumulation of the Campeche Marine Platform.