Costa Rica is known as a verdant, tropical paradise with rich rainforests, abundant wildlife, striking mountains and volcanoes, and picturesque beaches. However, the perceived abundance of Costa Rica’s water resources is only true for part of the country. The same geography and climate that bring abundant precipitation to most of southern Costa Rica and its Caribbean coast also leave the northern Pacific province of Guanacaste with substantially less rainfall and even periods of severe drought. This case study focuses on Guanacaste province, which is a major tourist destination as well as one of the country’s most productive agricultural regions. Water from the lush Caribbean slopes of the Lake Arenal region is transported across the continental divide through extensive infrastructure projects. Passing through the semi-arid regions of Guanacaste, hydroelectric power generation, extensive irrigated agriculture, and tourism development use most of the water, supporting a rapidly growing regional economy but leaving increasingly less water for environmental flows. This case study introduces students to “nexus thinking” to explore the multiple and overlapping water, energy, and food (WEF) demands and ecological challenges present in Guanacaste province. Each sector and its interconnections with other sectors are examined in turn through introductory lectures, and enriched by WEF systems thinking activities and class discussions. At the conclusion of this case study curriculum, students will be able to identify and characterize points of intersection, i.e., the nexus, of WEF supply and demand, and trade-offs that exist between WEF resources and biodiversity conservation.