The northeastern United States has episodic high ozone several times each year at locations remote from urban and industrial centers. Extended measurements of ozone and the ozone precursors, volatile organic compounds (VOC) and nitrogen oxides, were made at Acadia National Park, Cape Elizabeth, and other coastal Maine locations during the North Atlantic Regional Experiment (NARE) intensive. In addition, ozone was measured from a commercial ferry, the Scotia Prince, in the Gulf of Maine where ozone concentrations up to 129 ppb were observed. Two high-ozone episodes were observed during late August 1993 when ozone was greater than 90 ppb along much of the Maine coast. NOy concentrations at Acadia averaged 2.0 ppb (¿1.97), maximum 12.0 ppb. During the high-ozone episodes, NOy had linear relationships to ozone with slopes of 4--16. The timing of maximum values and extent of the high-ozone air mass suggests that urban plumes transported over the Gulf of Maine are brought inland by sea breezes to the coastal regions but not to the interior areas of Maine. ¿ American Geophysical Union 1996