The viewer allows to visualize interactively the data of chlorophyll-a concentration obtained monthly in the RADIALES cruises (called RADCAN or RCAN cruises for those carried out since 2013 at the three Cantabrian transects: Santander, Gijón, and Cudillero). The layout displays a sidebar, where you can select the desired option for a series of variables (station, size fraction, year, plot type, …) and a main panel where the graphs are displayed. It is organized into four tabs: [1] ‘Plot’ displays data from one single station (the complete list of the stations and their geographic coordinates are in https://seriestemporales-ieo.net, and are represented on a map in the fourth tab of this viewer). [2] ‘multipanel’ lays out together in the same figure the individual plots of all the stations, allowing for comparison among them. It allows to select the plot type. [3] ‘Sampling dates’ shows graphically the months, from the starting of the project, with chlorophyll data available. [4] 'Stations Map' displays the map with the positions of all stations.