The flow dynamics, volume, heat, and nitrogen transport, and water mass structure in the Northeast Channel (42°17′N, 65°58′W) are investigated using two years of moored velocity and temperature data. Measurements were made from September 1976 to September 1978 at three moorings across the channel just inside the sill with instruments at 100 m, 150 m, and 16 m off the bottom. Energetic water motions occurred at three time scales: 1) tidal frequencies; 2) low-frequency motions in the 4–10-day range; and 3) mean motions with periods of three months or longer. The dominant tidal constituent was the semidiurnal (M2) tide, whose elipses all rotated clockwise, with magnitudes ranging from 61 cm s−1 at 150 m depth decreasing to 41 cm s−1 16 m off the bottom. The low-frequency currents showed strong seasonal variability: In winter, these motions took the form of strong bursts of current up to 50 cm s−1 both into and out of the channel, and were the dominant subtidal motions; in summer, these bursts were s... Abstract The flow dynamics, volume, heat, and nitrogen transport, and water mass structure in the Northeast Channel (42°17′N, 65°58′W) are investigated using two years of moored velocity and temperature data. Measurements were made from September 1976 to September 1978 at three moorings across the channel just inside the sill with instruments at 100 m, 150 m, and 16 m off the bottom. Energetic water motions occurred at three time scales: 1) tidal frequencies; 2) low-frequency motions in the 4–10-day range; and 3) mean motions with periods of three months or longer. The dominant tidal constituent was the semidiurnal (M2) tide, whose elipses all rotated clockwise, with magnitudes ranging from 61 cm s−1 at 150 m depth decreasing to 41 cm s−1 16 m off the bottom. The low-frequency currents showed strong seasonal variability: In winter, these motions took the form of strong bursts of current up to 50 cm s−1 both into and out of the channel, and were the dominant subtidal motions; in summer, these bursts were s...