4. Saltwater Crocodile
The saltwater crocodile is the largest of their kind. An adult can grow up to 21 feet with reports that there are sightings of these crocodiles that are larger than 21 feet. Native to Southeast Asia and Northern Australia, saltwater crocodile can kill people with their deadly death roll. Saltwater crocodile is even more dangerous when they are in the water because they are fast swimmers.