An attempt was made to study the variations of an ecological parameter, water depth, and the effects of these variations on the foraging behaviour of waterfowl. 2 interconnecting freshwater ponds were chosen and marked into quadrants by corner stakes. Observing 3 quadrats from one pond and one from the second, the number of foraging dives per minute and the dive and pause times were recorded. Subsequent measurement of depth showed pond I 25-45 cm, pond II 52-74 cm. A significant difference in diving times was found (1.3 plus or minus 0.2 to 1.5 plus or minus 0.2 sec in pond I; 2.5 plus or minus 0.2 to 3.5 plus or minus 0.4 sec in pond II). Dives and pauses were longer and frequency of diving lower in deep water. While water, depth affected both dive time and pause time, the dive: pause ratio (a measure of efficiency) was similar for both ponds. It is pointed out, however, that the efficiency in terms of energy derived from food in relation to work put in to obtain may be affected in dives into deeper water.