Developing sustainable future islands depends on optimal integration of resources in a synergistic way. A nexus approach could help planners to understand potential trade-offs between resources. IDA3/5 model calculates the energy requirement for water-related activities, the water requirement for power generation, the land requirement for power generation and food grow. Different scenarios account for different technology composition and climate change scenarios. The study area of the model can be divided into sub-areas using a pyramid structure, and analysis can be done at different levels. The purpose of the model was to understand trade-offs between resource use and cascading affects in systems and services. The model has been originally developed in Matlab, currently is available in Matlab, Java and Python.