If you're thinking about hunting down under, make sure you find out once you have decided the animal(s), what clothing to bring and gear. In New Zealand it is easy to bring in your own hunting Bow, Muzzeloader or rifle (no pistol or military style firearm), with a permit sent to you before you come over.
At the airport police will open the case to have a look at the firearm then stamp your permit which they will take back when you leave the country. The permit costs $25 local dollars. Alternatively you can use one of the outfitters. Clothing for the seasons are the opposite of North America and Europe. With the main hunting season starting late February (end of summer) it can still be in 30c (86f) during the day. Weather starts cooling down from Late March which is when the Red Stag, Elk, Sika and Fallow start rutting. May-Sep weather gets from -5 (23f) to 15c (59f), this may not seem cold but the air can carry a lot of moisture in it and be extremely changeable as New Zealand is still only an Island but with very steep mountains in the south island (Southern Alps) where the Tahr and Chamois live. There are no predators as such, apart from you, so no snakes and spiders, very nice when camping out or walking in tall grasses.
In New Caledonia it never gets below 16 (60f) being a tropical island like Australia both 2.5 hrs from New Zealand. Australia does have some pretty nasty snakes/ spiders but very rarely will you see them. In the Northern Territories (top) there are Salt Water Crocs. I wouldn`t go swimming as they will cross parts of land into dams and do have a taste for any meat!
As far as firearms apart from Water Buffalo/Banteng in Aust. which require -375 or bigger all other big game can be hunted with anything from -270 up with 150 projectiles. Good all round calibers would be 7mm, 30-06, 300 family. Shooting distances will vary on animals from 50 yards-350yards and a lot of shots will be on hills up and down so practice will help here.
The hardest animal I would regard to bring down would be Sambar Deer, Tahr and Water Buffalo/Banteng. All this guys need good shot placement so take your time on the shot. The Tahr on foot (rut may-july) does require good fitness much like sheep hunting in Alaska, but helicopter drop off to camp is permitted and to hunt on the same day. Tahr with there very long and thick winter coats slows bullets down.
Hope this helps a little for those who are looking for a new challenge!