Upon making the descent from the ridge of the Great Rift escarpment, the first of the unique habitats you will encounter as you enter the northern edge of the park is the jungle like groundwater forest. Nurtured by a permanent supply of ground water from the area's high water table, a dense evergreen forest of mahogany trees and wild date palms tower overhead. Gnarled vines and mossy cover drape their branches, giving the forest an ancient and mysterious allure. Sunlight filters through the leafy canopy of foliage and dances over a verdant carpet of wild hibiscus, ginger, and other leafy plants that thrive in the moisture and shadows below. Abundant freshwater springs spill out from the wall of the Great Rift Valley, and moisture seeps from the volcanic rock into the water table just below the surface of the earth. Beautiful Antiaris and Quinine trees shoot up through the canopy from the forest floor, stretching their leafy arms to the heavens.
This rainforest like habitat could never survive if it wasn't for the permanent reservoir of water available. The water table here is high enough that it is easily tapped by the thirsty network of roots that zigzag below the dense growth. Otherwise known as a "swamp forest", the habitat found in this area can be quite boggy at times. In some places the water table is actually too high to support trees; in such areas the landscape gives way to marsh and swampy glades. Spiky reeds and star grass thrive in thick clumps around the quagmires, soaking in nourishment from the abundant water source beneath them.
In their book titled Among the Elephants , Iain and Oria Douglas-Hamilton write,
"The luxuriant forest could not be classified as a rain forest, since Manyara was a relatively arid area with an average rainfall of less than twenty inches. In fact, under such a climatic regime, it was only possible for the forest to grow because it was well-watered by innumerable streams. These issued from springs all along the foot of this part of the Rift wall, but the water originated some thirty miles away from the Ngorongoro Highlands. Rain falling there was prevented from running away too quickly by a thick cloak of mountain forest. It trickled down to the root and through layers of porous volcanic soil and rock, until it hit an impermeable layer of rock which finally surfaced at the foot of the escarpment within Manyara. Therefore, the Ground Water Forest, as it was named, with all its natural wealth, was dependent on water falling well outside it. If the Ngorongoro Forest were ever to be cut down the Manyara Ground Water Forest might well wither into extinction."
There are many places where the road is the dividing line between the ground water forest and the rift wall vegetation. As you drive into the park, you will notice the distinct difference between the towering forest on your left and a completely different type of vegetation on your right. The steeply rising slope on your right, strewn in granite boulders, is blanketed with entirely different types of trees and shrubs including the hulky forms of silvery baobab trees stretching their gnarled branches to the sky. The primitive looking Baobab tree has a massive, hollow trunk that collects rain water; the trunk also often serves as a cradle for a nest of wild bees. The Baobab's ancient forms looming next to the road seem to take on a personality of their own, and one won't doubt why they are fabled to be the dwelling place of ghosts or spirits.
Elephants, big fans of both water and vegetation, are commonly seen munching away in the groundwater forest. Shrieking blue monkeys chase each other through the leafy shadows, and inquiring vervet monkeys peer at you from the dense foliage. Many colorful birds flit between the shady branches of the trees here; one of the most brilliant of these birds is the lilac breasted roller, a vibrantly colored specimen with shimmering rainbow plumage of almost every hue. This habitat is especially ideal for baboons, who thrive in large troops here. These fascinating primates practice acrobatics in the surrounding trees, screeching with great enthusiasm in mock fights or demonstrations; they are also often seen drinking from pools of water formed by the springs or lounging lazily in the shade. Mother baboons trek down the road with inquisitive babies riding jockey style on their backs. These baby baboons may have never seen a human before and look quite endearing cocking their little heads in animated expressions of curiosity as they peer up at you with beady amber eyes.