Abstract: The invention relates in particular to a device for undersea collection of a light fluid the device comprising: a first tank that is provided with a first opening and a second opening; a second tank covering the first opening, surrounding a portion of the first tank, and provided with a third opening putting the second tank, into communication with the medium surrounding the device; connection means connecting together the first and second tanks: a first pipe opening out into the first tank in order to provide density transport of a phase of the fluid to the surface; a structure for guiding and introducing the fluid into the first tank, which structure extends inside the first tank and separates a first portion of the first tank in which the second opening is provided from a second portion of the first tank in which the open end of the first pipe extends; and a structure for collecting the fluid, which structure extends outside the first tank, is secured to the first tank, and surrounds the second opening.