This image shows various gravitational isopotentials (the blue surfaces) on Toutatis. A gravitational isopotential is a "level" surface, in other words, if you put a marble on one of these blue surfaces it wouldn't roll. Consequenty the blue surfaces correspond to different "altitudes" on Toutatis.
Another way to think of this image sequence is that it is what you would see happen if you left a garden hose running on Toutatis and created a Toutatian ocean (assuming you could neglect the gravitational effects of the water itself). The Toutatian lowlands fill up first while the Toutatian peaks stay dry the longest. Just before all the Toutatians drowned, they'd be confined to islands at either end of the asteroid.