Just because crocodiles are not visibly present does not mean that an area is safe to swim. In fact, crocodiles that view humans as prey usually hide at the first sign of humans (i.e. a car parking or footsteps.)
A 6-meter-long crocodile can lie completely invisible in less than a foot of muddy water.
Large crocodiles have the strongest biting force of any animal alive- exceeding 5000 psi.
Most attacks by large crocodiles are over within a few seconds or less.
Most human victims succumb to drowning long before dismemberment and consumption take place.
Crocodiles become more aggressive during the mating season.
Crocodiles can move very quickly over short distances on land.
Crocodiles won't hunt their prey on land over a distance longer than a couple of feet. They don't have a high stamina and don't want to waste energy. If you can escape their first strike and run a couple of meters, you are usually safe.
Crocodiles are adept at learning and memorizing routines, such as the location of nearby campers or the routes of travelers.
In water, crocodiles tend to drag their prey under and drown them.
Crocodiles can slow their metabolism to such an extent that a tree with an intruder hiding in its branches may be guarded continuously for several weeks, without breaks for food.
Crocodiles have strong muscles for closing their jaws and holding them shut, but weak muscles for opening them.
There is a sensitive flap in a crocodile's throat, known as the glottis, which they use for breathing. As a result, as with some other predators, forcing the arm into the throat may encourage release, although this is not certain by any means and may instead lead to the arm being severed.
Sometimes, an attacking crocodile will bite, hold on, and then rapidly spin its body to weaken its prey or tear off limbs (the "death roll").
When crocodiles see prey, they will duck under the water and when they reach their target, jump out and bite
Bear Close Up, at Dubai Wildlife Park