The Big Flat Brook is a picturesque trout stream located in northwestern New Jersey, renowned for its clear, cold waters and scenic surroundings. Originating at the Saw Mill Lake Dam in High Point State Park, the river flows southwesterly for approximately 20 miles before joining the Delaware River at Walpack Bend near the hamlet of Flatbrookville. The Big Flat Brook is part of the larger Flat Brook system, which includes its main tributary, the Little Flat Brook.

Paddling opportunities on the Big Flat Brook are limited, as it is primarily known for its excellent trout fishing. The river is generally characterized as flatwater, but paddlers should exercise caution and check water levels before attempting any trips. The main stem offers a peaceful float through forested landscapes and occasional riffles, suitable for canoes and kayaks during periods of higher water.

The Big Flat Brook is famous for its trout fishing, supporting populations of brook, rainbow, and brown trout. The river's overall quality habitat and abundant forage, including minnows, sculpin, dace, and various aquatic insects, contribute to its reputation as one of New Jersey's premier trout streams. Anglers can expect to find stoneflies and caddis flies, making it an excellent destination for fly fishing enthusiasts.

A notable feature of the Big Flat Brook is its 4.2-mile Catch and Release Section, which starts at the Route 206 Bridge and ends at the Roy Bridge on Mountain Road. This stretch is strictly regulated for artificial lures and fly fishing only, preserving the quality of the fishery and providing a unique angling experience.

Access points along the river include the put-in at Saw Mill Lake Dam in High Point State Park and various bridges and public areas along its course. The nearby towns of Layton and Walpack provide services for visitors. The river flows through Stokes State Forest, offering additional recreational opportunities and scenic beauty.

The Big Flat Brook holds historical significance as part of the Walpack Valley and the broader Minisink region, areas rich in Native American and early European settlement history. Today, it serves as an important ecological resource and recreational destination in northwestern New Jersey.

Anglers and paddlers should be aware of fishing regulations, particularly in the Catch and Release Section. Additionally, users should respect private property boundaries and be mindful of changing water conditions, especially after heavy rains. While multi-day paddling trips are not common on the Big Flat Brook itself, the area offers opportunities for extended stays combining fishing, hiking, and exploration of the surrounding Delaware Water Gap region.

The best times to visit the Big Flat Brook are typically spring and fall when water levels are favorable and trout are most active. However, the river's cold waters and diverse insect life support year-round fishing opportunities for those willing to brave varying conditions.