[26] Results of a phylogenetic study supports its likely origin in Africa and later radiation towards Southeast Asia and the Americas; it genetically diverged from its closest recent relative, the extinct Voay of Madagascar, around 25 million years ago near the boundary between the Oligocene and Miocene.

[36][37] The largest skull of a saltwater crocodile that could be scientifically verified was of a specimen in the Muséum national d'Histoire naturelle, collected in Cambodia.

[50] Furthermore, a research paper on the morphology and physiology of crocodilians by the same organisation estimates that saltwater crocodiles reaching sizes of 7 m (23 ft 0 in) would weigh around 2,000 kg (4,400 lb).

[37] The saltwater crocodile has the greatest size sexual dimorphism, by far, of any extant crocodilian, as males average about 4 to 5 times as massive as adult females and can sometimes measure twice her total length.

[19][27][67] The saltwater crocodile inhabits coastal brackish mangrove swamps, river deltas and freshwater rivers from India's east coast, Sri Lanka and Bangladesh to Myanmar, Malaysia, Brunei, Indonesia, Philippines, Timor Leste, Palau, Solomon Islands, Singapore, Papua New Guinea, Vanuatu and Australia's north coast.

[93] Because of its ability to swim long distances at sea, individual saltwater crocodiles appeared occasionally in areas far away from their general range, up to Fiji.

Though other crocodiles also have salt glands that enable them to survive in saltwater, a trait that alligators do not possess, most other species do not venture out to sea except during extreme conditions.

[94] Generally very lethargic, a trait that helps it survive months at a time without food, the saltwater crocodile will usually loiter in the water or bask in the sun during much of the day, preferring to hunt at night.

[100][101] Like most species in the crocodilian family, saltwater crocodiles are not fastidious in their choice of food, and readily vary their prey selection according to availability.

[104] In addition to these prey, juveniles also take a variety of freshwater and saltwater fish, various amphibians, crustaceans, molluscs, such as large gastropods and cephalopods, birds, small to medium-sized mammals, and other reptiles, such as snakes and lizards.

[35][109] Mammalian prey of juveniles and subadults are usually as large as the smaller species of ungulates, such as the greater mouse-deer (Tragulus napu) and hog deer (Hyelaphus porcinus).

It preys on agile wallabies,[113] golden jackals, viverrids, turtles, flying foxes, hares, rodents, badgers, otters, chevrotains and pangolins.

[114][115] A rare incidence of an adult 2.6 m (8 ft 6 in) long saltwater crocodile preying on an Indian porcupine was reported in Sri Lanka.

[27] In Australia, the saltwater crocodile's taste for feral pigs and buffalo was a key factor in their recovery for hunting pressures over the last fifty years according to studies published in 2022 by Dr. Marianna Campbell et al.,.

[96][130][131][132][133][134] However, there is evidence that saltwater crocodiles do hunt while out in the open seas, based upon the remains of pelagic fishes that dwell only miles away from land being found in their stomachs.

[96][27] Young saltwater crocodiles are capable of breaching their entire body into the air in a single upward motion while hunting prey that may be perched on low hanging branches.

[135] Large prey is then torn into manageable pieces by "death rolling", the spinning of the crocodile to twist off hunks of meat or by sudden jerks of the head.

[136] Occasionally, food items will be stored for later consumption once a crocodile eats its fill, although this can lead to scavenging by interlopers such as monitor lizards.

[9][150] While adults have no natural predators, baby saltwater crocodiles may fall prey to monitor lizards (occasionally, but not commonly, the numerous goanna in Australia, and the Asian water monitor (Varanus salvator) further north), predatory fish (especially the barramundi (Lates calcarifer)), wild boars, rats, various aquatic and raptorial birds (e.g. black-necked storks (Ephippiorhynchus asiaticus) and white-bellied sea eagles (Haliaeetus leucogaster)), pythons, larger crocodiles, and many other predators.

[151] Juveniles may also fall prey to tigers and leopards (Panthera pardus) in certain parts of their range, although encounters between these predators are rare, and cats are likely to avoid areas with saltwater crocodiles.

[154] Illegal hunting still persists in some areas, with protection in some countries being grossly ineffective, and trade is often difficult to monitor and control over such a vast range.

However, many areas have not recovered; some population surveys have shown that although young crocodiles are present, fewer than 10% of specimens spotted are in adult size range and do not include any particularly large males, such as Sri Lanka or Palau.

[155][156] In a more balanced population, such as those from Bhitarkanika National Park or Sabah on Borneo, 28% and 24.2% of specimens observed were in the adult size range of more than 3 m (9 ft 10 in).

[162][161] The low level of attacks may be due to extensive efforts by wildlife officials in Australia to post crocodile warning signs at numerous at-risk billabongs, rivers, lakes and beaches.

[169] This number may be conservative in light of several areas where humans and saltwater crocodiles co-exist in relatively undeveloped, low-economy and rural regions, where attacks are likely to go unreported.

[27][39][169] Despite their reputations, many wild saltwater crocodiles are normally quite wary of humans and will go out of their way to submerge and swim away from them, even large adult males, if previously subject to harassment or persecution.

[169] In the Andaman Islands, the number of fatal attacks on humans has reportedly increased, possibly due to habitat destruction and reduction of natural prey.

[176][177] In July 2018, a 600-strong mob slaughtered 292 saltwater and New Guinea crocodiles in Papua province in Indonesia in a revenge attack after a man who encroached upon the sanctuary was devoured.

[179] Aboriginal rock art depicting the saltwater crocodile is rare, although examples of up to 3,000 years old were found in caves in Kakadu and Arnhem land, roughly matching the distribution of the species.

This section is dedicated to examples of the largest saltwater crocodiles recorded outside scientific norms measurement and estimation, with the aim of satisfying the public interest without creating data pollution, as well as serving an educational purpose of guiding the reader to separate fact from possible fiction.