Despite a public interest in naming species extending back thousands of years, and over 250 years of a standardised naming system, at least 12,000 new species (plus fossils) have been named per year in the past decade. More marine species were described in the past decade than any previous decade. Biodiversity databases that list the names of almost all marine (and most non-marine species) and provide geographic distribution data on over half of all known species, were used to estimate global patterns in species richness and taxonomic effort, and how many more species remain to be named. Data on 65,000 species from the Ocean Biogeographic Information System showed sampling bias, and geographic and latitudinal patterns in species richness and endemicity. The results help answer questions about whether most species on Earth will be in the oceans, deep-sea, be microscopic (< 1 mm), and/or extinct before they are discovered; provide a global map of marine biogeographic realms; and raise questions about causes of species richness patterns.