Every year, more than a million wildebeests migrate throughout Tanzania and Kenya in 
search of fresh vegetation and water. I have never seen an event more amazing than watching a wildebeest migration. Watching a wildebeest migration is like watching an ant colony on a large scale (see picture on the right). They move one by one through the Serengeti. If there is too large of a gap between two wildebeests, they actually run to close that gap. If there is a storm in the distance, you can be sure that the wildebeests will head in that direction for the fresh rain water.
The most dramatic scene of the wildebeest migration is when they do a river crossing. We were very fortunate and saw a river crossing within a few moments of being in the Serengeti. When the migration reaches the Mara River, the wildebeests spend a lot of time contemplating crossing the river. It is dangerous for wildebeests to cross the river. A wildebeest could lose its footing on the rocks and break its leg. If this happens, the wildebeest will drown. The other danger is crocodiles. They prey on wildebeests as they cross, especially young wildebeests. The wildebeests could spend hours on the edge of the river just thinking about crossing. A few times we watched them get close to the water, only to have something scare them away. However, when they start crossing (sometimes with the assistance of the zebras, who are among the wildebeests and appear to be more brave by crossing first), it is game on and they all start running at once across the river. The wildebeests come from everywhere and a crossing could last a while because there are so many. The most dramatic of the five crossings we saw came during the last one. As the crossing began, we saw a crocodile in the water. A young 
wildebeest was super close to it and at one point was even standing on top of it (see picture on the left). We were all holding our breaths and hoping that the young wildebeest would make it and not die in front of our eyes. It was so intense. It turned out that the crocodile must have been well-fed already, because it made no move to attack any of the wildebeests. The young wildebeest made it to the other side safely! I am happy to report that while many wildebeests lose their lives crossing the Mara River every year, we did not witness any loss of life first hand. On the other side of the river, wildebeests connect with their families that they lose track of during the crossing and the migration continues.
The Great Morrison Migration 