Arusha National Park is small. It has lots of open forest of short trees, a few areas of savanna, and a bit of rain forest. It includes a crater and several small lakes. We were there on a cool, cloudy day, but it never quite rained on us. The roads were muddy, though. At one really muddy spot, we passed a Land Rover full of local Tanzanian ladies wearing dresses (hey, why not? You don't really get out of the car except to eat lunch...). Our guide made a joke in Swahili to their guide that at least if he got stuck, all those "mamas" could get out and push. He got a big laugh.
We did not see as many animals as in Tarangire and Lake Manyara, but considering this was a quick day-trip-with-a-picnic-and-home-by-5:00, it was pretty amazing. We saw giraffes, cape buffalo, zebras, warthogs, baboons, flamingos, blue monkeys, and a couple of bush bucks off in the distance.
This park is known for colobus monkeys, though, and that's what I was really hoping to see. They are black and white with lush, long fur and look like long-limbed skunks perching in the trees. As we drove into the first little bit of rain forest, our guide slowed way down and was scanning the trees and muttering, "Where are you today?" We drove out of the forest, and I thought maybe we would miss the colobus monkeys that day. But on the way to the picnic area, we passed through another bit of forest and found them!