Plum Island Sound is a coastal estuary separating Plum Island from the mainland of Massachusetts. It is a saltwater sound characterized by extensive salt marshes, numerous winding creeks, and sandy beaches along the Plum Island shore. The area is largely encompassed by the Parker River National Wildlife Refuge, offering a paddling experience focused on wildlife observation within a protected coastal environment. The sound is a popular destination for motorized boats, so paddlers should expect some boat traffic and associated wakes, particularly within the marked channels. The many inlets and side channels can be visually confusing, especially at lower tides, making a map or GPS advisable for navigation. Tides significantly influence conditions, with lower tides exposing extensive shallows and sandbars, which can strand paddlers or limit routes. Currents are present, mild within the sound itself, but the nearby mouths of the Merrimack, Parker, and Rowley Rivers can have challenging and potentially dangerous currents, warranting caution and local knowledge. A primary access point for paddlers is at the Parker River National Wildlife Refuge, specifically from a launch site opposite Parking Lot 1 near the refuge entrance at 6 Plum Island Turnpike in Newburyport. There is a vehicle entry fee for the refuge, though holders of a National Parks Pass enter for free. Parking can be challenging during midsummer. Another noted launch is the state boat launch where Route 1 crosses the Parker River, though the Newbury Town Launch on High Street is restricted to permitted residents only. Paddlers are advised that landing on the Plum Island Sound-facing beaches within the wildlife refuge may be prohibited to protect wildlife, though postings can be unclear. The area is known for abundant birdlife, seals, deer, and insects like greenhead flies during their season, requiring bug protection. Guided tours are available from local outfitters like Plum Island Kayak, which operate on protected waters within the sound and adjacent rivers, with tour timing specifically coordinated with the tides.