Abstract: A fluid sampling device includes a tube, one end of which is adapted to be placed into a fluid medium. An actuator on the opposite end moves a rod along the longitudinal axis of the tube to bring a stopper into and out of sealing engagement with the fluid receiving end of the tube. With the fluid receiving end open, it is placed beneath the level of the fluid. The pressure of the fluid causes fluid to enter the tube to the level of the surrounding fluid. Then the stopper is closed, thus sealing the fluid sample within the tube, so that the sample may be removed. A stopper for sealing the upper end of the tube may also be provided, with the actuator moving both the upper and lower stoppers. The tube is formed of polypropylene extruded to 0.050 inches .+-.0.005 inches and the stopper is formed of neoprene coated with polytetrafluoroethylene.