We report the results of determinations of tidal periods from spectral analysis of the voltage induced across an unpowered length of the TAT-7 telecommunications cable in the North Atlantic Ocean over an approximately 19 day interval. Particularly prominent spectral components are observed at several frequencies, including those identified as corresponding to the diurnal declination luni-solar (K1), semi-diurnal principal solar (S2), semidiurnal principal lunar (M2), and monthly lunar (Mm), components. In addition, a large amplitude spectral component of high statistical significance was observed at a frequency of 3.0051 cpd, approximately one-third the sidereal day. This component does not appear to be related to the solar component S3 and possibly corresponds to a declination luni-solar K3 frequency, although the amplitude is very much larger than that which might be expected. Other common lunar tides appear to be a minor component of the data. Such cable data can be used for studies and refinement on a global scale of large-scale tidal (ocean and ionosphere) models.