Data were obtained as part of the Bermuda Atlantic Time-series Study (BATS) in order to characterise the environmental context of the ecosystem. They were collected on board of the R/V Atlantic Explorer, at BATS site (31°40′N; 64°10′W) on a monthly basis, from March 2016 to May 2017, except in March 2017 due to rough weather. Environmental samples were taken during the day, except in February 2017 when they were taken at night. Environmental data were collected vertically using a SeaBird 911 CTD rosette equipped with temperature (°C), conductivity (mS/cm), fluorescence (RFU), oxygen (µmol/kg) and Photosynthetic Active Radiation (PAR, µE/m²s) sensors. Density (σθ) was calculated from temperature and conductivity. Depth of the Deep Chlorophyll Maximum (DCM, m) was defined as the maximum of the fluorescence profile. Three types of Mixed Layer Depth (MLD, m) were calculated. A seasonal and a depth zone characterisation were obtained from MLD, DCM and density measures. The depth (m) at which the light intensity was equal to 1% of the surface light intensity was also computed.