Down Under Land
From the Super Mario Wiki
Down Under Land is a large swampland that bears a good resemblance to the country of Australia, and is located somewhere on Mushroom World. Down Under Land is rather bizarre in appearance, as the whole place appears to be upside-down by nature, with the ground floating in the air and the actual "ground" resembling the sky, giving new meaning to the term "Down Under". Despite this, Down Under Land is quite inhabitable, and is home to many exotic creatures, including Birdoroos, crocodiles, and the occasional koala bear. Natural features of Down Under Land include a river with rough waters, towering trees and several caves. Man-made features include a small town populated by Mushroom People and a series of boardwalks.
 The Magic Statue
Early Mushroom settlers of Down Under Land found that the crocodiles that lived there were a serious threat to anyone who set foot in their swamp. As such, they had no choice but to either find a way to repel the crocodiles, or leave. They somehow came across a Magic Statue that could repel crocodiles away from their town, and were able to live peacefully.
 Crocodile Attack
Kangaroo Koopa eventually learned about the Magic Statue, and deliberately traveled to Down Under Land just to steal it so that the crocodiles would return and eat all the citizens there. Mario, Luigi, Princess Toadstool and Toad also learned of the Magic Statue, only they wanted to learn if they could use it to protect the Mushroom Kingdom. Kangaroo Koopa barely beat them to Down Under Land, swiped the Magic Statue, and left just as the four heroes arrived.
Crocodiles soon invaded the town, and chased everyone there except Mario and Luigi atop the general store. While the crocodiles proceeded to chew the entire general store down to ground level, Mario and Luigi escaped from the town and built a raft, which they used to travel down a river. After narrowly dodging Birdoroo Egg attacks and Boomerangs thrown by Koopa Troopas, Mario and Luigi ditched the raft just before it crashed into several large rocks.
Mario and Luigi stumbled across the footprints of crocodiles that were being scared away by the Magic Statue, and followed them in reverse to find Kangaroo Koopa and the Magic Statue, which they stole back from him. Mario and Luigi managed to get the Magic Statue back to town, and were able to repel the crocodiles with it. The crocodiles chased Kangaroo Koopa out of town, and the people there were able to live in peace once again.