The Mind Polje is centrally located in this Estremenho Karst Massif region, and plays a Key role in the complex hydrology of the region. Upstream of the Polje we find the Mindinho - Olho de Mira, Moinhos Velhos - Pena - Contenda and Lomba - Regatinho cave systems, and downstream of the sink holes in the Polje we find three major springs; Alviela, Vila Moreira and Almonda. SPE (Sociedade Portuguesa de Espeleologia) have been studying and exploring these cave systems for decades in an attempt to understand the complex water flow dynamics from the caption areas, through the Polje, across blocking areas to the final discharge springs.