They don’t have a single, natural confluence anymore.
The Darling River is the Murray’s longest tributary. Historically, most Darling flow reached the Murray via the Great Darling Anabranch (a 460-km ancestral channel) near Wentworth, NSW.
Today, regulation (Menindee Lakes, weirs, extractions) means the Darling often fails to reach the Murray. When it does, it’s via the Anabranch or the engineered Darling–Murray junction at Wentworth—managed, not natural.
The Murray itself continues 100 km to the Southern Ocean at the Coorong/Lake Alexandrina.