The Carmans River is a scenic waterway located on Long Island, New York, flowing approximately 10 miles from its origin at Upper Yaphank Lake southward to its mouth at Bellport Bay. This river system includes Upper and Lower Yaphank Lakes before transitioning into the main river channel. Paddling opportunities on the Carmans River are diverse, with three main sections: the Yaphank Lakes to Upper Carmans River (1-2 miles), the Upper Carmans River (2-3 miles), and the Lower Carmans River (5.4 miles). The entire river offers flatwater paddling suitable for all skill levels, though the upper portions can be challenging due to narrow, shallow sections. The river's difficulty ranges from easy to moderate, with the upper sections requiring more maneuvering and occasional portaging in low water conditions. The lower section, flowing through Wertheim National Wildlife Refuge, provides a more open and easier paddling experience.

Spring and fall are ideal paddling seasons, offering comfortable temperatures and higher water levels. Summer paddling is popular but can be crowded, while winter paddling is possible for experienced cold-water paddlers. The Carmans River ecosystem supports diverse wildlife, including various bird species, fish, and turtles. Paddlers often encounter great blue herons, ospreys, and even bald eagles. The surrounding vegetation includes native wetland plants and deciduous forests.

Key landmarks include the historic Yaphank Lakes, the tranquil stretches of the Upper Carmans River, and the expansive Wertheim National Wildlife Refuge. The river passes through several Long Island communities, including Yaphank and Brookhaven. Primary access points include Upper Yaphank Lake near exit 66 of the Long Island Expressway, Carmans River Canoe and Kayak in Brookhaven (2979 Montauk Highway), and various points within the Wertheim National Wildlife Refuge. The nearby town of Brookhaven serves as a hub for river activities.

Historically, the Carmans River played a crucial role in early Long Island settlements and industry, powering mills and supporting local agriculture. Today, it's valued for its ecological significance and recreational opportunities. Safety considerations include checking water levels, especially in the upper sections, and being aware of tidal influences in the lower river. Non-motorized boating is permitted, but regulations may vary in different sections, particularly within the wildlife refuge. While multi-day trips are not common due to the river's length, paddlers can easily combine sections for full-day adventures, exploring the diverse ecosystems from the lakes to the bay. The Carmans River offers a unique opportunity to experience Long Island's natural beauty and rich history through a peaceful paddling journey.