Cetacean brains have long been of scientific and general public interest, not only because of their large size but also due to their high gyrification degree – often related to their complex social lifestyle. Despite Brazil’s vast biodiversity, the country lacks comparative studies of brain morphology in general, preventing a more systematic understanding of brain anatomy and the evolution of its diverse species. To solve this, we have established a network for collecting and analyzing stranded Brazilian cetaceans’ brains. Through this initiative, we currently have approximately 50 specimens representing 11 genera, 5 families, and 14 species, originating from 14 research institutes. Using ultra-high-field magnetic resonance imaging and state-of-the-art methodologies, we are analyzing diverse and complementary aspects of brain morphology at intra and inter-specific levels. Now, we have an unprecedented opportunity to analyze and give a first brain description for species such as the Guiana dolphin (Sotalia guianensis) while also providing updated data for well-known species such as the Bottlenose dolphin (Tursiops truncatus). Furthermore, this effort marks the inaugural imaging of endangered river dolphin species, such as the endemic Amazon River dolphin (Inia geoffrensis) and the Tucuxi (Sotalia fluviatilis), highlighting the now available data for comparative analysis between riverine and marine dolphins. The structural and volumetric data of a large variety of cetacean brains including those already collected and those planned for acquisition will bridge important gaps in the scientific literature, yielding a more complete description of the diversity of the brain not only for cetaceans but for mammals in general.