The Klasop or Klasof is a river in the northwest of the Bird's Head Peninsula of New Guinea. Its course generally runs in a southerly direction, and it flows into the bay of Segun, in a large estuary that is connected to that of the Klasagun River to the west. The large island of Jemur separates the two estuaries. The stream of Klawaralim is a left tributary in the upper reach, while in the lower reaches Klasop is joined by a number of right-hand tributaries, including Klamer and Klasafet. For much of its length, Klasop is surrounded by mangrove forests.
| Klasop Klasof | |
|---|---|
 The Klasop and Klasagun estuary | |
| Location | |
| Country | Indonesia |
| Province | Southwest Papua |
| Regency | Sorong |
| Physical characteristics | |
| Mouth | Segun Bay |
• coordinates | 1°25′02″S 131°19′09″E / 1.417088°S 131.319086°E |