Estimating the accurate position of the shoreline over time can be challenging. We propose a new approach to delimit the shoreline from remotely sensed images simply and accurately. This approach treats pixels as simultaneous radiometric measurements and, by examining the distance between iso-radiometry lines, assumes the shoreline in the position where the radiometric behavior changes more suddenly. The analyses conducted applying this coastline extraction approach underscore its significant flexibility. Specifically, the approach yields promising outcomes even if applied to a variety of different and dissimilar types of remotely sensed products. Indeed, the approach’s intrinsic straightforwardness and low computational load qualify it as a promising tool for time-series production.