This letter reports the finding of giant aerosol particles (with radii greater than 1 &mgr;m) composed mainly of sulfur over the equatorial Pacific Ocean. The sample also contains many modified sea-salt particles. Since the air mass had been over the open sea for more than 10 days, these giant sulfur-dominant particles may have been formed in the marine boundary layer or transported from the free troposphere. ¿ American Geophysical Union 1995