Islands, due to their limited territory, are also limited in the resources available to them for the development of regular life. Spain can be included here, with an archipelago that is itself an outermost European region—the Canary Islands. The Canary Islands have unique characteristics due to richness in groundwater and the use of desalination to support water demand, which rises primarily due to agriculture and the tourism sector. However, the Canary Islands face significant environmental challenges, particularly in the management and preservation of their water resources. One of the most pressing issues is the contamination of coastal aquifers, primarily due to the intrusion of seawater. This problem is exacerbated by inadequate wastewater treatment facilities and the escalating reliance on desalination processes. The latter, while essential, demands a high energy consumption, posing sustainability and environmental concerns, especially in the context of the global push towards reducing carbon footprints. Therefore, this article analyses the current status of water resources in the Canary Islands, as well as future challenges that will arise in a scenario of climate change, where temperatures are expected to increase in Spain.