Iodine-132 was used as a tracer to demonstrate that ozone causes iodine vapor to be released from the sea surface. This rate of release was porportional to ozone concentration in the range 0–100 ppb and depended on mixing of the water phase. At the mean ozone concentration existing at the sea surface the rate of iodine release was equivalent to an annual contribution of 6 to 12 × 10¹⁰ g to the atmosphere. This estimate is subject to uncertainties arising from inadequate knowledge of the mean concentration of iodide at the sea surface and the effect of mixing of the surface sea water on the rate of release of iodine. The significance of such a contribution to the iodine budget of the atmosphere is discussed.