$S^3$ (Super Separator Spectrometer) is a device proposed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams, which will provide in a first phase of SPIRAL2 ions with A/q = 3, can reach intensities exceeding 100pµA for lighter ions (A< 40 − 50) depending on the final choice of the ECR (Electron Cyclotron Resonance) ion source. These unprecedented intensities open new opportunities in several physics domains, e.g. super-heavy and very-heavy nuclei, spectroscopy at and beyond the dripline, multi-nucleon transfer and deep-inelastic reactions, isomers and ground state properties and nuclear molecular resonances. An international collaboration interested in the aforementioned physics has been formed for developing technical solutions for this new instrument.