The development of the Swampwalk is nearly complete. For the past two years, volunteers working under the town’s direction have been gradually installing a raised wooden walkway above a portion of the 47-acre marsh area off Locust Street that the town owns. On Saturday volunteers were scheduled to install the final section of the 1,421-foot walkway, according to Susan Fletcher, the town’s assistant director of planning and human services. Separate sections of the walkway were previously built from the Danvers Rail Trail to two islands in the swamp — Tall Pine Island and Fletcher Island — and from Fletcher Island to an observation platform. The final portion of the walkway connects Tall Pine Island to the observation deck, completing the loop, according to Fletcher. The Swampwalk is for the recreational enjoyment of the public and for educational use by local schools. Fletcher said the town plans to eventually add benches. The project, which was approved by the Danvers and Wenham conservation commissions, has been carried out with the help of a $26,660 state grant.