Last time I was up in Nhulunbuy was in 1995 on "Exercise K95". My unit's role was to defend the town (and it's Bauxite mine) from the "Orange Forces". (played by SAS blokes, some of whom were sadly killed a few months later in the Blackhawk Disaster in Townsville)
I was leading a security patrol around the outskirts of the coastal town, which is partially divided by a natural lagoon, about 20 metres wide. Rather than manoeuvre the patrol of 10 soldiers spread a couple of hundred feet apart around the lagoon, I sent the forward scout straight across the lagoon. The water was only about chest deep, and as it was so hot, the scout didn't complain.
He waded across the lagoon and was climbing up on the opposite bank when we all simultaneously froze. We'd all heard a noise that was a cross between a loud snort, and an exhalation, about 20 feet from my scout, who was by now legging it up the opposite bank. We then saw a massive salty casually swimming out to open water. I'm not going to estimate it's size, but at the time it looked fcuking huge. I've seen pics of monster crocs before, and I reckon that this thing was just as big.
I then decided that we'd patrol around the lagoon and eventually catch up with my scout, who for some reason, was looking a tad pale when we reached him. He'd found some footprints that he wanted to show us, so we crept closer to the bank and were horrified (in a manly way.........) when my scout dropped his "bush hat" into one pawprint, and the hat's OD was still a fair bit smaller than the paw's ID.
We continued on with our patrol, and one of the locals eventually sidled up to my scout and asked him if he'd been in the lagoon. When the scout answered in the affirmative, this old bloke told us that we were all very lucky, the salty we'd seen was a local identity and over it's 100(+) year history, it had taken several human victims. He wasn't sure why it didn't eat my scout, but opined that it might have eaten recently and wasn't really interested in dessert.
Either way, we took a wide berth around the lagoon on future patrols............