The MASSIMAL dataset contains data from shallow coastal areas collected using multiple data modalities, such as hyperspectral and multispectral aerial imaging, underwater imaging, and sonar measurements. The dataset was collected at four main locations along the Norwegian coast, in the time period 2021-2023, spanning large variations in habitat types. The data is organized as a set of ZIP files, with each file corresponding to one single time, location, and data type. Annotations of hyperspectral images are also included in the dataset. Potential applications of the dataset include development of mapping methods for coastal habitats, education on coastal monitoring methods, and reference material for timeline studies. See README.md and https://github.com/mh-skjelvareid/massimal-dataset for a more comprehensive introduction to the dataset.