Temporal variation of some physical and chemical observations was performed during four days with six hour of intervals at two fixed stations at the Enseada do Flamengo, Ubatuba, São Paulo. The salinity (34.3‰ - 35.1‰) and temperature values (about 26ºC) are typical of local coastal waters. The dissolved oxygen shows super saturation content with some exceptions. The nitrogen (nitrite and nitrate) forms have very low values, with a maximum of 1.0 µg-at/l (nitrate). Other nutrients, like phosphates (0.15 - 0.80 µg-at/l) and silicates (5.0-21.5 µg-at/l) and the relationship N:P (1:3)3 show the poor terrigenous contribution and small bioproductivity. The pH and alcalinity was normal for sea water.