Lung Lon ancient canal has been ‘forgotten’ for decades, even though it could be considered one of the most important archaeological features of Oc Eo settlement and culture in Southern Vietnam. Recent research conducted by the Center for Archaeology, Southern Institute of Social Sciences in 2018 - 2019 at Lung Lon has contributed to elucidating the forgotten past in this ancient urban centre. In addition to the archaeological excavation, the project also applied geological and geophysical survey using electromagnetismc (EM) to identify the depth and the width of the canal, as well as traces of habitation along the canal banks. The results of AMS radiocarbon dating and the geological study demonstrated that the area in and around Oc Eo was affected by relatively high sea level during the period 6,000 - 4,000 years BC. The establishment and development of the Oc Eo settlement along the Lung Lon canal occurred between the 1st and the 6th Centuries CE. Lung Lon canal was used as a waterway for boat traffic connecting ports along the coast with inland settlements such as Oc Eo. Some types of special artifacts collected in cultural layers of Lung Lon such as the hundreds of thousands of Indo-Pacific glass beads, gold-glass beads, mosaic beads from Rome, coloured ceramics of Indian origin, imported ceramics from China, and Wu Zhu (五銖) coins illustrate Oc Eo’s importance, and its relationship with maritime trading networks, from around the 2nd to – 5th Centuries CE. This paper introduces recent research on the Lung Lon ancient canal, aiming to raise awareness of the significant role this waterway played in the life of Oc Eo residents.