The entire wilderness of remote Cobourg Peninsula, including the surrounding sea, forms the Garig Gunak Barlu National Park. It's a stunning, isolated place and one of the loveliest spots on Australia's northern coast. You'll likely see dolphins and turtles and − what most people come for − a threadfin salmon thrashing on the end of your line.
On the shores of Port Essington are the stone ruins and headstones of Victoria settlement − Britain's 1838 attempt to establish a military outpost here. It's an eerie place, echoing a doomed dream to build a city in such remote country.
Fishing is big business up here, and fishing charters and tours often come in search of mackerel, coral trout, trevally, threadfin salmon and barramundi. Boat hire is possible in a couple of places, but you're better off organising it through one of the tour companies before you arrive.
The waters of Garig Gunak Barlu National Park are home to six species of marine turtles – green, loggerhead, olive ridley, hawksbill, flatback and leatherback; some of these nest on remote beaches in the later months of the year. In the park's inland billabongs, watch for the northern snake-necked turtle. Whales, dolphins, various shark species and saltwater crocodiles are all found in the waters off the coast – swimming here would be extremely dangerous.
Mammal species, though elusive, are always possible to see, especially around dawn, dusk and overnight. Species include dingoes, echidnas and northern brown bandicoots. The park is also home to more than 200 bird species.
There are two camping grounds in the park with shower, toilet, BBQs and limited bore water; generators are allowed in one area. Camping fees (per person per day $16.50) are covered by your vehicle permit, but if you fly in you'll have to pay them. Other accommodation is available in pricey fishing resorts.
Permits to visit the Cobourg Peninsula are handled by the NT Parks & Wildlife Commission. It can also arrange permission for you to stay overnight in the national park. The camping fee is $232.10 per vehicle, which covers up to five people for seven days and includes a camping and transit pass (the transit pass on its own costs $88). This fee must be paid six weeks before you intend to travel.