A collection of raw dive computer data (latitude, longitude, date, time, minimum temperature, surface temperature and maximum depth) logged by unknown recreational divers and uploaded to a publicly available online dive logging application (divelogs.de) was exported and filtered for further analysis. The data were spatially restricted to the northern Red Sea: 23-30° N, 32-39.4° E. Only dives within standard recreational depths (maximum dive depth ≤ 40 m), years with more than 75 dives per year and with a spread of dives across most months were retained (2000 to 2017). The data were processed in R version 4.2, using the tidyverse suite of packages. A 15 arc-second (approximately 0.5 km) resolution bathymetric grid of the area was downloaded from GEBCO, allowing bathymetric depths associated with each dive location to be found using the marmap get.depth function in R. Data were collected as part of Celia Marlowe’s PhD project at the University of East Anglia, which aimed to assess the precision and accuracy of water temperature profiles collected from devices commonly carried by Scuba divers. The PhD project was part of the Next Generation Unmanned Systems Science (NEXUSS) Centre for Doctoral Training, funded by the Natural Environment Research Council (NERC) and the Engineering and Physical Science Research Council (EPSRC) (NE/N012070/1), and was additionally supported by Cefas Seedcorn (DP901D).