About 3km from Ea T’ling townlet, Cu Jut district, and about 20km from Buon Ma Thuot City along Road No.14, Bang Rup rapids is about 150m wide on a section also that long of the Krong No River (Father River) – a tributary of the “back flowing” Serepok River – the natural boundary between Dak Nong and Dak Lak provinces.
In rainy season, the high water is quite strong, but partially conceals the roughness of the rapids. In dry season, the gentler flow twists among large and small basalt blocks, some being tens of meters in size, lying sprawled on both the banks and in the river, seemingly thrown away by a giant man. The sense of “sprawling” becomes even clearer when examining each block, which is made up of hundreds, even thousands, of small polygonal columns. The columns are a few tens of centimeters in diameter and a few meters in length, arranged in parallel, either quite straight or twisted within a block, but very different from block to block, resulting in a “sprawling” arrangement.
There could be several different explanations for this formation, of which the “meeting between fire and water” appears most reasonable. The hot lava when reaching the river quickly cooled and solidified, becoming unable to flow further. The still hot lava behind then had to find its own way, either overlapping or spreading out the cold lava. Subsequent cooling caused the lava to shrink, resulting in polygonal cracks and columns. It is remarkable that such cracks always develop inward and downward, perpendicular to the surface of the cooling lava. Their sprawling indicates how rugged and uneven this surface was.
The M’nong and Ede indigenous people also have legends to explain the formation and existence of the rapids. In particular, it was the fight between the Gods of Leng Sang (Dray Sap waterfall), Leng Nur (Dak Nur waterfall), Leng Gung N’tao (seven-storey waterfall) and Leng Mrok God (Bang Rup) due to his arrogance, aggression and annoying the lives of all species and people in his ruling area. The constant war caused heavy damage for the troop of Leng Mrok God, leading to the sprawling of the rock army like today.