We measured the sulfur gas dimethylsulfide (DMS) in marine air at a coral cay on the Great Barrier Reef. DMS is well known to be released from the world's oceans, but environmental evidence of coral reefs releasing DMS has not been clearly demonstrated. We showed the coral reef can sometimes release DMS to the air, which was seen as spikes above the DMS released from the ocean. The DMS from the reef supplements the DMS from the ocean to assist formation of clouds that influence local climate.