In French Guiana, access to clean drinking water is a growing challenge despite the region being one of the most water-rich places on Earth. Although the Amazon basin receives an average of 3,000 millimeters of rainfall annually and has over 112,000 kilometers of rivers, the increasing frequency of droughts and the lack of understanding of groundwater resources are creating a crisis. This situation is not just due to water scarcity but also reflects the differing ways in which communities access water. Those living along rivers have long relied on them for water, food, and transport, while urbanized areas on the coast depend on river intakes and artificial water treatment systems. The coastal regions, where most of the population resides, face a unique challenge: during the dry season, saltwater from the Atlantic Ocean can intrude into freshwater sources along the rivers. This phenomenon, worsened by rising sea levels and longer droughts, makes river water unsuitable for consumption and requires moving water intakes further upstream. However, these adjustments are costly and difficult for local communities to manage. According to reports from the Court of Audit and the Senate in 2025, the funding allocated for drinking water and sanitation in French Guiana is only 27% of what is needed, a gap that would not be tolerated in any other region of Metropolitan France. In contrast, the interior of French Guiana remains largely unstudied, with little data on its groundwater resources. Populations in isolated areas like Grand-Santi, Maripasoula, and Antecume Pata still rely heavily on river water, which is often contaminated and requires complex treatment that is hard to maintain in remote villages. Groundwater, which is less prone to surface contamination and requires less treatment, has emerged as a potential solution. However, these sources are fragile and vulnerable to seasonal changes and river flooding. In areas further inland, crystalline basement rocks hold water in aquifers, but these are poorly understood and difficult to access compared to regions like Brittany in France. Gold mining, a major industry in the interior, is further degrading water quality by creating massive amounts of sediment and contaminating rivers. This, combined with climate change, which is projected to bring longer and more intense droughts and floods, is making the situation even more critical. To address these challenges, there is a growing recognition that diversifying water sources and improving the understanding of groundwater in the region is essential. With existing research partnerships and European funding, French Guiana has the potential to become a regional leader in water management in the Amazon, provided that efforts to expand knowledge and research continue.