This is another popular question, and true to form it generates enough popular myth and misconceptions to fill the stomach of a large Deinosuchus. Running crocodiles evoke images of slavering reptiles chasing people down for lunch, and there are some wild figures that are often quoted - speeds over 40 mph are regularly quoted by some books, television documentaries and enthusiastic tour-guides. Don't be misled! Crocodiles have unique ways of getting around, but let's be realistic and look at this properly.
The truth is, if you see a crocodile running towards you then it's easy enough to evade. It's when you don't see it coming that you're in danger! A crocodile's greatest strength is not its endurance and stamina on land, but it's ability to launch a surprise attack when you're least expecting it. In other words, crocodiles cannot afford to give their prey the chance to flee - fleeing prey (on land at least) is normally dinner lost.
Never under-estimate the attacking speed of crocodile from a standing start, and never under-estimate how fast they can move when running away from you! Read on...
There are three main "gaits" (styles of locomotion) that describe how crocodilians get around on land. The "belly crawl" is typically a fairly slow gait in which the crocodile slides over a slippery substrate such as mud, using its legs to push itself along on its belly. However, this gait can be modified to shift that bulky body at impressively high speeds, normally away from a threat. "Belly run" becomes a more appropriate description of this faster gait, where the legs still operate on either side of the body rather than from underneath it.
The next gait is the "high walk" (left), which is uniquely crocodilian - resembling the erect gait of a mammal with the legs directly underneath the animal, rather than the splayed gait of a reptile. This is a slow means of getting around, but it is very useful for picking the bulky body off the floor to negotiate obstacles or to avoid the friction induced by scraping the belly against non-slippery substrates such as soil or rock. The high walk is normally used for short distances, but long-distances hikes are quite possible. You can see a video of a high walk here (hit the "BACK" button in your browser when you're done).
When moving quickly away from a threat, crocodilians employ one of two methods on land. The first is the faster "belly run" which I've already mentioned, in which the legs move very rapidly in a typically reptilian pattern to propel the crocodile forward. During this belly run, the crocodile starts to move its body in a sinusoidal manner along the horizontal plane, almost as if it were swimming. This flexion adds power to the stride by helping to position the limbs for the greatest leverage when they contact the ground. The power of the body torsion contributes to the power of the stride. It also enables the crocodile to transition quickly into a swimming style once it begins to enter the water.
The second rapid locomotory gait on land is called "galloping" (left). The form of this gallop is quite unique, with front and hind limbs moving as synchronous pairs. As a result, the crocodile bounds almost like a rabbit - hind legs moving together to push the animal forwards and into the air, and then the body bending so the front legs absorb the impact, while the hind legs move forward for the next bound. This style of running has been seen in a several species (Australian freshwater crocodile, New Guinea crocodile, Nile crocodile, American crocodile, Cuban crocodile, African dwarf crocodile) although it is more common in smaller individuals of these species. Other species, even under extreme stress, simply resort to a rapid belly run which is significantly slower than a gallop except over mud. Galloping is used primarily as an escape response on firm ground, and enables the animal to leap over low obstacles as it heads towards the water. However, a few boisterous individuals (eg. Cuban crocodiles, Australian freshwater crocodiles) have been known to attack a threat by galloping towards it - quite an intimidating experience! You can see several videos of galloping here (hit "BACK" in your browser when you've finished to return here).
So, now you have an idea of how crocodiles can run. But how quickly can they run? Most crocodiles can achieve speeds of around 12 to 14 kph for short periods, which is somewhat slower than a fit human can run. Don't believe the hype - if you're reasonably fit, you can definitely outrun a crocodile! Even faster are galloping crocodiles, and Australian freshwater crocodiles have been clocked at just over 17 kph over distances of perhaps 20 to 30 metres before they begin to tire. In these cases, the crocodile is running away from a threat - only certain extinct species of terrestrial crocodyliforms regularly hunted using a similar gait, which perhaps explains its origins.
However, crocodiles can accelerate much faster than this over very short distances by exploding into action - I have measured adult saltwater crocodiles (around 4 metres total length) moving at 12 metres per second for a quarter of a second, which is long enough to capture prey standing within one body length before it even has time to react. This is where crocodiles excel - launching themselves into motion from a standing start, hoping to cover the short distance between themselves and their prey before the prey can react. This isn't running, however, because the crocodile cannot maintain this acceleration for more than a very brief instant.
Bear in mind that crocodiles do not normally chase their prey - their typical hunting strategy is one of surprise, lunging at prey and capturing it in a single fluid movement. Secondly, crocodiles have a relatively low stamina and their physiology does not permit sustained exercise. When a crocodile runs, it is nearly always away from a potential threat and into the water (see photo). Adult males and females defending their territory or a nest may pursue an intruder, but this is normally over a short distance until the intruder has retreated a sufficient distance. Be aware that crocodilians are not the sluggish creatures they are often portrayed to be, and can move very rapidly when they need to. However, they can not run around at speeds most cheetahs would be proud of.
MYTH! It is often said that you can outwit a crocodile by running in a zig-zag fashion away from it. This isn't true! Humans can out run crocodiles on land, and a straight line is the fastest way of putting distance between yourself and the crocodile. Most crocodile attack victims never see the crocodile coming - they use surprise, not speed.
You can learn a lot more about crocodilian locomotion in the GENERAL BIOLOGY section of the Crocodilian Biology Database.