The Gulf of Mexico (GoM) is a shared resource at risk, with the following major problems: (a) freshwater use and shortage, (b) pollution, (c) habitat modifications, (d) unsustainable development of living resources, (e) global change e.g., sea level rise, temperature increase and change in rainfall patterns, (f) public education, and (g) lack of political interest. Throughout the 6,134 km of coastline from Florida, USA, to Quintana Roo, Mexico, major geographic regions (GR) are: (a) the warm-temperate GoM, (b) the tropical GoM, and (c) the Caribbean coast of Mexico related to the GoM. In the GR, discrete complex systems can be defined as "geographical/hydrological sub-regions" which result from the interactions of geologic, geomorphologic, oceanographic, climatic, freshwater basin drainage, physical chemical gradients, coastal vegetation, wildlife, estuary-shelf interactions, and human factors. The ecosystem approach as a management tool is predicated on ecosystem functioning coupled with environmental sustainability of economic development of the coastal zone, both in the U.S. and Mexico. The challenge for the future GoM coastal management should be towards a combination on Integrated Coastal Management (ICM) with Large Marine Ecosystem (LME) management, and these can be demonstrate through a conceptual model.