Great Bay is a vast and complex tidal estuary system located in southeastern New Hampshire, extending inland from the mouth of the Piscataqua River. It encompasses over 6,000 acres of open water, including Little Bay and the tidal portions of several major rivers like the Lamprey, Squamscott, Winnicut, Bellamy, Oyster, and Cocheco. As one of the most recessed estuaries on the East Coast, it features a dramatic tidal range that exposes more than 50% of its mudflats at low tide. The average depth is about 9 feet, with deep channels carving through the system to depths of nearly 60 feet. The estuary is a dynamic mix of saltwater from the Gulf of Maine and freshwater from its tributaries, creating a rich mosaic of habitats including salt marshes, eelgrass meadows, rocky shores, and deep channels. The entire system is part of the Great Bay National Estuarine Research Reserve, managed for long-term research, education, and stewardship, and all Reserve lands are open to the public for fishing.