Across the Mighty Mekong
Virtually all the area south of Saigon is part of the Mekong Delta. It is hot, humid, and ultra-wet. The land is some of the most fertile on earth for an endless variety of fruits, grains, other vegitation as well as aquatic animal life and foods (fresh water and salt water variety)
The entire region is spider-webbed with small, localized canals and waterways twenty to thirty feet wide and not much more than 12 to 15 feet deep during the rainy season. Those types of "rivers" seem always to come to mind when mentioning the Brown Water Naval operations in that area.
But there are some major tributaries of the Mekong River that are nearly a mile wide and can admit ocean-going vessels without trouble. Those were the parts of the Mekong that were the most intriguing to me.
The area around Can Tho is especially rich with river trade, and Can Tho will soon be developed into a comercial sea port rivelling Saigon and even Hanoi. In order to get to Can Tho from Saigon, one needs to cross several major tributaries, and commercial ferry is the only way to do that.
This picture depicts a typical ferry for hauling vehicular and human traffic across vast river expanses.
This picture depicts a typical river sections of the ultra-wide variety.