Running through the heart of the park and marking the northernmost point in the park that most visitors are allowed to visit, the Galana River, which combines the waters of the Tsavo and Athi Rivers, cuts a green gash across the dusty plains. Surprisingly few visitors make it even this far and sightings of crocs, hippos, lesser kudus, waterbucks, dik-diks and, to a lesser extent, lions and leopards are relatively common. Watch out also for the distinctive Somali ostrich.
There are several places along the flat-topped escarpments lining the river where you can get out of your vehicle (with due caution, of course). Most scenic are Lugards Falls, a wonderful landscape of water-sculpted channels and striated rocks, and Crocodile Point, where you may see abundant crocs and hippos. The trail that runs from the falls back to Voi follows a river and is good for wildlife-spotting, but the track is often impassable after rain.
The area north of the Galana River is dominated by the Yatta Escarpment, a vast prehistoric lava flow which is estimated by some to be the longest lava flow in the world at 300km. It's only accessible at present for those with a special permit.