The Marikina River is a significant waterway located in the eastern part of Metro Manila, Philippines. It flows through the city of Marikina and serves as a natural boundary between several municipalities. The river is approximately 27 kilometers long and is an important source of water for the surrounding communities. Historically, the Marikina River has played a vital role in the local economy, supporting activities such as fishing and transportation. However, it has also faced challenges, including flooding during heavy rains. Efforts have been made to improve the river's condition and promote environmental sustainability in the area.