The Cobourg Peninsula is well-known among fishers for its fabulous barramundi fishing in March, April, October and November, while wildlife-watching is excellent during the Dry (the Peninsula is very difficult to access at other times).
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'd be 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 turtle: green, loggerhead, olive ridley, hawksbill, flatback and leatherback; some of these nest on remote beaches in the later months of the year. Watch for the northern snake-necked turtle in the park's inland billabongs. 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, 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.