Small wood panels treated with many different chemicals have been exposed to limnorian and teredine marine borers in the sea at Key West, Florida. These preservatives and treatments include creosotes with and without modification, waterborne salts, salt-creosote dual treatments, chemical modifications of wood, and modified polymers. In spite of the accelerated nature of this test, many treated panels remain free of attack after 13-1/2 years in the sea. Untreated panels have been badly damaged by marine borers in 6 to 18 months. Borer activity has lessened in recent years.