This circuit is also called the circuit of the warm valleys. It has a leafy vegetation and rich fauna. It covers the southwest part of the province, the lowest part of it, and eco tourism and adventure tourism become interesting alternatives here.

It comprises the San Pedro, Santa Barbara and Ledesma Departments, and part of the Valle Grande Valley. The San Francisco valley, along with the Calilegua, Zenta, Santa Barbara, Centinela and Maíz Gordo mountain ranges, are also part of its uneven terrain.

The waters of the Rio San Francisco River (formed by Grande and Lavayen rivers, and tributary itself of the Bermejo river) are intensely used for irrigation.

Due to its geographical location, the Yungas (Cloud forests) have a sub tropical damp and warm climate, which allows for the flourishing of an abundant vegetation and rich fauna. It is a country of hot spring of exceptional healing significance, such as the one from Aguas Calientes (Caimancito) and the Laguna La Hedionda lagoon, which have therapeutic properties, especially for the skin, due to its sulphur contents.

It displays an important economical activity and it is represented by agriculture (sugarcane, citrus, vegetables) and the industries associated to it: sugar refineries (Ledesma, La Esperanza, Rio Grande) that process sugar, alcohol and paper; along with citrus concentrate factories as well as several sawmills.

This route presents a clear and defined tourist structure that tacks attractions with a clear ecological vocation along an axis signed by National Parks, Reserves and existing Biomes.

Over the Ruta Nacional Nº 34 National Route, the cities of San Pedro and Libertador General San Martin can be found, and there the Ledesma sugar refinery, and integrated industrial complex producing paper and energy from the residue, can be visited.

It is a region with very high temperatures during southern hemisphere's summers and with abundant precipitations. It is a region inviting to mystery and continuous astonishment.