The river has its origin in the south slopes of the Khentii mountains near the Burkhan Khaldun mountain in the Khan Khentii Strictly Protected Area, about 180 km northeast of Ulaanbaatar. This area is the watershed between the arctic (Tuul river) and pacific (Kherlen, Onon) basins and named Three river basins.
From there the Kherlen flows in a mostly eastern direction through the Khentii aimag. On its further way it crosses the eastern Mongolian steppe past Ulaan ereg and Choibalsan, entering China at 48°3′N 115°36′E, emptying into Khulun nuur.
Kherlen bridge is located nere Baganuur 130 km from Ulaanbaatar.
The cache is a small plastic container box containing a Mongolian souvenirs, pencil and a log book