Route 172 is a 16 km (9.9 mi)-long mostly north–south secondary highway in southwest New Brunswick, Canada.

From there, it runs west to the community of St. George and passes the Magaguadavic Basin.

From there, the highway goes south through a mostly forested area before passing the west shore of Scotch Bay.

In Back Bay, the route takes a sharp turn heading west towards the small community of L'Etete.

It L'Etele, Route 172 takes a sharp turn south past Matthews Cove and finally the route heads west to the Deer Island Ferry to Deer Island.