A traveler walks through the mud in search of Vietnam’s southernmost point in the Mekong Delta province of Ca Mau

A group of tourists searches for the Mekong River’s lost estuary and seeks Vietnam’s southernmost point.

But if you look on a recent map, you’ll see only eight mouths running into the sea.

One of the Mekong’s two distributaries in Vietnam, the Hau River, is supposed to empty into the sea via the Tran De, Dinh An and Bach Sac estuaries, according to old maps.

But the Bach Sac doesn’t appear on maps these days. We’ve set out to see if it still exists.

When we reach the shores of the East Sea in Soc Trang, our group leader, Dau An Viet Tourism Company (Vietmark) marketing director, Truong Hoang Phuong, begins discussing the locations of the three estuaries with locals.

As a geography and map expert, Phuong finds that most people haven’t heard of the Bach Sac, with only a few elders recalling it by its former name - “Bat Xat.”

The locals say the Bach Sac hasn’t flowed into the sea for decades. They say silt buildup on Dung Island has swallowed the mouth of the Bach Sac.

Sure enough, when we get to the site of the former mouth near Dung Island, the water that used to flow through Bach Sac has been diverted to the Con Tron Canal.

Leaving Soc Trang, we head for Ca Mau Province to locate Vietnam’s southernmost tip using a global positioning system (GPS).

Many people think the southernmost tip of Vietnam is the Ca Mau Cape. But the cape has in fact always been northwest of the true southernmost point, Phuong says.

After two hours of slogging through the swampy mud – sometimes frighteningly like quicksand – we’re up to our waists in it near Khai Long Beach.

Phuong points out to sea and says his coordinates are 167 meters farther south.

We decide not to risk drowning in mud and declare the soft land we stand on be the southernmost tip of Vietnam.

Reported by Thuy Linh