Our team of 20 scientists who study the biology of marine invertebrate animals (i.e., animals without backbones) boarded the R/V Nathaniel B. Palmer in San Francisco, California on 24 September 2020 and embarked on a 14-week voyage to Antarctica ending in Punta Arenas, Chile on 18 December 2020. During the expedition, we sampled and studied marine invertebrates living in some of the most remote but fastest changing seas on the planet. The team explored the biodiversity, evolution, and biogeographic patterns of animals living in the Weddel Sea and Bransfield Strait. Now, back in the lab, morphological and molecular tools are being used to assess Antarctic invertebrate biodiveristy, unrecognized genetic variation, and patterns of relatedness between populations of marine Antarctic species.