Narrow Bay is a coastal bay located off Mastic Beach on the south shore of Long Island. It is accessible from the Smith Point County Park launch site, which features a paved ramp and parking for approximately twenty vehicles. Suffolk County permits and fees may apply for using this access. This launch provides entry to both Narrow Bay to the east and Bellport Bay to the west. Paddling conditions in Narrow Bay are heavily dependent on weather, tide, and motorboat traffic. The bay is subject to significant tidal currents, particularly near the Smith Point Bridge, where standing waves often form. The timing of the tide in the bay lags behind Moriches Inlet by several hours, a critical factor for planning. Paddlers must account for this delay to anticipate current strength and direction. Recreational motorboat traffic can be significant, especially on summer weekends, requiring constant vigilance.

The bay is exposed to winds and open to the Atlantic Ocean via Moriches Inlet, creating potential for challenging conditions. A notable safety incident involved a capsized kayaker who was not wearing a personal flotation device and required rescue for hypothermia, underscoring the importance of preparedness for cold water immersion even in winter months. The water is saltwater and subject to full tidal influence. The area near Pattersquash Island was mentioned in rescue operations. For beginners, the bay can be suitable under friendly conditions but becomes more challenging with wind against tide, warranting careful assessment before departure.