With the two year drought in Sabe Sands and Kruger National Park a couple of years ago, the existence of water holes is a key for the survival of the wildlife there. Some of the water holes were dried up and forced many of its wildlife "residents" to seek other water holes. Of course, those water holes are already "owned" by others and the only way to survive is in battle. We saw an example of that when a hippo, in search of a new water hole, presumably did battle with another hippo only to lose. That is not surprising, as the hippo probably had to walk a long distance in the heat, weakening him as it prepared to fight.
Water holes represent survival to many. We were lucky to spot a herd of elephants one late evening that our guide said was heading to a local water hole. Sure enough, that is where they were headed. As they got close, they began to start running to their oasis. We were lucky enough to watch (and photograph) them drink and cool themselves off. A short respite for the herd in the wild.