A cầu khỉ ("monkey bridge") in Vietnam is a handmade bamboo or wooden passway across a stream or gully.
In coastal areas of the Red River Delta in northern Vietnam, such as Giao Thủy, Hải Hậu, ... (Nam Định Province) or Tiền Hải (Thái Bình Province) there are also footbridges, mainly for passersby to take care of rice in the fields.
They would naturally follow the path of foot traffic, the bridges wading out of the water stream.
Now in industrialized regions sometimes there is a "Competition on passing Cầu khỉ by bicycle" for remembering the taste of footbridges.
Such a competition took place in Cửa Lò town, Nghệ An Province in March 2016.