In 1966 Congress passed the National Sea Grant College Program Act to promote marine research, education, and extension services in institutions along the nation's ocean and Great Lakes coasts. In Maryland a Sea Grant Program -- a partnership among federal and state governments, universities, and industries -- began in 1977, and in 1982 the University of Maryland was named the nation's seventeenth Sea Grant College.The Maryland Sea Grant College focuses its efforts on the Chesapeake Bay, with emphasis on the marine concerns of fisheries, seafood technology, and environmental quality.Increasingly divers -- especially military and commercial divers -- are required to enter waters that may pose a range of hazards, including heat, radioactivity, and chemicals. Both recreational and professional divers may also encounter microbial hazards because of the presence of poorly treated or untreated sewage, for example.This book pulls together presentations by experts in the field, including researchers, professional divers, and physicians, to shed light on the extent and nature of hazards confronted by divers as they enter uncertain waters.