What does a hippopotamus eat when it leaves the water at night?

When a hippopotamus leaves the water at night, it travels along familiar paths into surrounding grasslands to graze.12

Although they spend much of their time submerged in water, hippos do not feed while in the water. Instead, they spend five to six hours each night grazing on grass, consuming approximately 35 kg (80 pounds) of vegetation per night. To graze, they grasp the grass with their tough, wide lips and jerk their heads to pluck it. In areas near rivers where they graze and trample frequently, they may denude large areas of grass, which can lead to erosion.12