Andrew, are you sure the croc is only thirty feet? Salt water crocs can get up to 40 feet but thats the rare exception these days. We have them in the very southern part of the everglades, Floridia and even on occassion, Key West.
Per Wikipedia, the largest Australian saltwater crocodile on record is 20.6 feet, though a number of other sites (include National Geographic) report specimens up to 7 meters, which would be 23 feet. From what I know, the American saltwater crocodile is a different, and smaller, species.
It has been years since I reviewed the film, so I am not certain where my stated length came from. It could have been stated by one of the characters. I will say that the picture of the crocodile on the flatbed trailer at the end makes like look larger than thirty feet, as I think trailers are around 50 feet in length or so.
