The EOL (Environmental Observation of the Littoral) buoy is operated since 2013 in the bay of Villefranche-sur-Mer (France, 43°40'54.0"N 7°19'10.8"E). This buoy (3.6 m wide, 4 tonnes), equipped with solar panels, allows performing, in an autonomous way, measurements of physico-chemical parameters on a mooring mode (2.5 m depth). This buoy was developed as part of a partnership between the Observatoire Océanologique de Villefranche (OOV; now Institut de la Mer de Villefranche, IMEV) and the company Mobilis. Data transmission is performed on a daily basis and data stored on a server on land (http://www.obs-vlfr.fr/data/view/eol/surface/). The buoy is currently involved in the COAST-HF network as part of the Coastal Ocean and Nearshore Observation French Research Infrastructure (ILICO). In particular, the buoy is equipped with a Sea-Bird SBE SMP-ODO deployed at the surface (2.5 m). An extra CTD is available in order to rotate during calibration at the manufacturer. Underwater cleaning of the sensors is performed on a monthly basis. In addition, a proper cleaning in the lab is performed three times a year. The site where the buoy is deployed is visited (100 m away from the buoy) on a weekly basis as part of the SOMLIT network. In the framework of SOMLIT, casts are performed with a CTD properly cleaned after each use and calibrated on a yearly basis. Salinity data from the buoy are corrected based on these extra-measurements. Furthermore, discrete sampling is performed for the measurements of oxygen (Winkler method) in order to inter-calibrate the respective sensors on the buoy. From 2022-11-25 to 2023-05-04 and from 2025-01-15 to 2025-02-06, missing temperature data from CTD were replaced by temperature data coming from respectively a seaFET pH sensor (SeaBird) and a piSAMI pH sensor (Sunburst Sensors, LLC) placed at the same position under EOL buoy than the CTD. In this dataset, dissolved oxygen measurements were corrected. The correction was performed using weekly discrete samples analysed by Winkler titration (Winkler, 1888), which were considered reference measurements. Sampling was conducted approximately 300 m from the EOL buoy at the Point B station within the french coastal monitoring network SOMLIT (Service d’Observation en Milieu LITtoral).