VOLCORE_2021 is an update on the original VOLCORE data released in 2020. Change notes are listed within the VOLCORE_2021 data file. A major update is the new merged Layers-Holes-AgeDepth sheet, enabling easier manipulation of the data. The VOLCORE (Volcanic Core Records) database is a collection of 34,696 visible tephra (volcanic ash and associated products) occurrences reported in the initial reports volumes of all of the Deep Sea Drilling Project (DSDP; 1966-1983), the Ocean Drilling Program (ODP; 1983-2003), the Integrated Ocean Drilling Program (IODP; 2003-2013) and the International Ocean Discovery Program (IODP; 2013-present) up to and including IODP Expedition 381. The combined international drilling programmes (OD) have locations with global coverage. Cored tephra layers and tephra-bearing sediments span timescales from recent to ~150 million years in age. This database is a collection of information about reported visible tephra layers entirely or predominantly composed of volcanic ash. Data include the depth below sea floor, tephra thickness, location, and any reported comments. An approximate age was estimated for most (29,493) of the tephra layers using available age-depth models. The database can be applied to tephrochronology, volcanology, geochemistry, studies of sediment transport and palaeoclimatology.