The River Calder is a river located in West Yorkshire, England. It flows through several towns, including Wakefield and Castleford, before joining the River Aire. The river is approximately 30 miles long and is known for its scenic beauty and recreational opportunities. Historically, the River Calder played a significant role in the industrial development of the region, providing water for mills and factories. Today, it is a popular spot for activities such as fishing, walking, and cycling along its banks, contributing to the local community's outdoor lifestyle.