The anthropogenic greenhouse effect and the associated temperature rise of the planet represent the main challenging issue for the Earth sciences of the next century. Marine ecosystems are a key component of the Earth system, as they modulate the transfer of greenhouse gases (mainly CO2) to the ocean surface. Moreover, oceanic ecosystems mitigate the effects of anthropogenic carbon injection into the atmosphere, via the so-called “biological pump”. Ocean biogeochemistry is hence confronted to a major challenge: the determination of the extent and efficiency of the climatic feedback of the carbon “biological pump” within the context of climate change. A new type of float, the “ProvBio”, has been developed jointly by Ifremer and the French company KANNAD, following the scientific directives of the Oceanographic Laboratory of Villefranche (LOV). The ProvBio design has been achieved from the Provor-CTS3 float, adding miniaturized, low power consumption, and quite neutrall y buoyant optical sensors for biogeochemical measurements delivered from Satlantic and Wetlabs manufacturers. This article describes the first results at sea