Don't worry too much about the saltwater crocs getting up to 7 metres or more in length, it's the rest of them you have to worry about...
"Sweetheart was the name given to a 5.1 metre saltwater crocodile responsible for a series of attacks on boats in Australia between 1974 and 1979. Sweetheart attacked outboard motors, dinghies, and fishing boats. In July 1979, Sweetheart was finally caught alive by a team from the Territory Parks and Wildlife Commission, but drowned while being transported when it became tangled with a log."
Quoted from
Sweetheart wiki page. The story of this croc was loosely adapted for the 2007 movie '
Rogue'
More here
http://www.nt.gov.au/nreta/museums/s...art/index.html
Have a look down the page at the stomach contents, specifically the first animal (known to be particularly alert and suspicious creatures here especially around waterholes and rivers - that croc was crafty
).