The Republic of Vanuatu, a small archipelago of island Melanesia, is home to 138 distinct Oceanic languages, for which we provide here a new list and map. This updated figure, obtained by combining earlier sources and more recent information from experts, makes Vanuatu the country with the highest language density in the world, whether compared to its land surface, or to its population. This modern density is not due to genealogical diversity, but reflects three millennia of in situ diversification from a single ancestor, Proto Oceanic. This historical process took the form of multiple linguistic innovations that spread across the dialect continuum in entangled patterns, bringing about the mosaic we know today. Vanuatu’s linguistic diversity is now increasingly threatened by the spread of the national language, Bislama. The various chapters in this volume describe and discuss some of the cultural and linguistic features that make Vanuatu such a diverse archipelago.