Hancock Pond is the largest pond of the Hancock Brook chain. The narrow-gauge railroad followed the east shore of the pond through West Sebago. The remainder of the pond is in Denmark. The railroad maintained a water tank adjacent to the pond which was a favored stop during summer excursions when passengers would swim in the pond. Subsequent shoreline development with residences and seasonal cabins has caused increased algal blooms in the pond. The pond supports the same fish species found in Sand Pond, since the thoroughfare between the two ponds allows easy passage at similar pond elevations. Hancock Brook overflows a dam at the southwest corner of Hancock Pond into a boggy area including small Mud Pond and crosses the town line from Denmark into Hiram before reaching Middle Pond approximately downstream. Hancock Brook downstream of Middle Pond forms the town line between Hiram to the west and Sebago to the east.
Barker Pond
The railroad crossed Hancock Brook at the north end of Barker Pond downstream of Middle Pond, to follow the west shore of Barker Pond. The old railroad grade has been converted to an automobile road known as the Narrow Gauge Trail. Fish swim downstream from Hancock Pond into Barker Pond, but nutrient enrichment causes dissolved oxygen deficiency below the summer thermocline limiting suitability of the pond for trout. Hancock Brook is entirely within the town of Hiram after overflowing a dam at the southwest corner of Barker Pond. Sebago Road and Wards Hill Road cross the brook at Rankins Mill downstream of Barker Pond. A granite masonry archrailroad bridge crossed the brook downstream of Rankins Mill. The last crossing of the brook is by Maine State Route 5 in Hiram just above the confluence with the Saco River.
Tributaries
Sucker Brook drains Perley Pond and Pickerel Pond into the north end of Hancock Pond. With depths of and, respectively, these ponds support native populations of chain pickerel and have been stocked with largemouth bass. The Maine Department of Fish and Wildlife has stocked Perley Pond with legal sizebrook trout for cool weather angling, but these trout are not expected to survive warm summer temperatures. Southeast Pond drains into Barker Pond from Baldwin.