Name the body of water that borders Australia to the north.

The body of water that borders Australia to the north is the Arafura Sea. This sea lies between northern Australia and the island of New Guinea. It is an important geographic feature as it connects the Timor Sea to the north with the Coral Sea, which lies to the east. The Arafura Sea is significant not only for its geographical location but also for its ecological diversity and the various marine species it supports.

In the context of the other bodies of water listed, the Coral Sea is to the east of Australia, while the Savu Sea is located further to the northwest, and the Bass Strait lies to the south, separating Tasmania from the mainland. Thus, the Arafura Sea is the correct choice for identifying the northern border of Australia.