During the period of 1990--1992, year-round oceanographic observations were conducted in the vicinity of L¿tzow-Holm Bay, East Antarctica. It was found that the thickness of the Winter Water (WW) layer, characterized by a cold fresh oxygen-rich water, exhibits its maximum in the austral fall (typically 500 m) and its minimum in the austral summer (typically 350--400 m). The associated density variation of the water column explains only about one third of the seasonal variations in sea level at the coast, which suggests a large seasonal variation in barotropic coastal flow. Prominent freshening occurs in the WW layer during fall. This appears to be caused by the accumulation of WW, whose upper portion is freshened in the preceding summer. These seasonal variations appear to occur every year. We propose that the seasonal variation in the WW layer is mainly caused by the seasonal variation in the wind over the coastal ocean. In fall the prevailing easterly wind intensifies, which increases the Ekman convergence of WW in the coastal ocean, while in summer the opposite occurs. ¿ American Geophysical Union 1996