SYNOPSIS. A free vehicle is a timed and weighted device released from a ship in a free fall to the ocean bottom. Instruments carried on the free vehicle have been built to take biological samples, sediment samples, water samples, and photographs, and to measure currents, tides, and temperature. The instrument then returns to the surface where it is recovered by the ship. A free vehicle system for biological sampling in the deep sea is described in detail. It consists of a mast assembly, flotation, hookline and traps, and a magnesium release attached to weights. Different types of magnesium links used include a rod, a wire on pliers, and a series of diamond-shaped beads that drop through a hole after dissolving. A deck plan for launching the free vehicle and its retrieval at sea are described.