Dear Colleagues, We are very happy to share our new dataset, the Northumberland Dolphin Dataset 2020 (NDD20). This dataset would be of particular interest to those wishing to utilise machine learning models for mammal re-identification or the development of automatic photo-id systems, such as Siamese Neural Networks or more conventional Convolutional Neural Networks. Please see below for details: We introduce the Northumberland Dolphin Dataset 2020 (NDD20), a challenging image dataset annotated for both coarse and fine-grained instance segmentation and categorisation. This dataset, the first release of the NDD, was created in response to the rapid expansion of computer vision into conservation research and the production of field-deployable systems suited to extreme environmental conditions - an area with few open source datasets. NDD20 contains a large collection of above and below water images of two different dolphin species for traditional coarse and fine-grained segmentation. All data contained in NDD20 was obtained via manual collection in the North Sea around the Northumberland coastline, UK. NDD20 was released at this year’s FGVC7 Workshop as a part of CVPR2020. Our accompanying paper can be accessed at https://arxiv.org/pdf/2005.13359.pdf, with the dataset itself available at https://doi.org/10.25405/data.ncl.c.4982342. On behalf of all coauthors, Cameron Trotter c.trotter2@ncl.ac.uk Cloud Computing CDT & Marine MEGAfauna Lab, Newcastle University, UK