One of the advantages to being in a small boat to photograph crocodiles, is the ability to compose shots of the animal swimming towards you. This is also where having a competent lookout is handy too.
This shot is from the Mary River up in the Northern Territory of Australia. I was using an a700 with a 300/4 G prime for these shots. This guy is about 3 metres long. No idea about its gender however :)
Clicking the image will bring up a slightly larger version.