Ha Pak Nai is a wetland area in the Yuen Long District of Hong Kong, surrounded by mountain ranges and faces Shenzhen Bay. Ha Pak Nai is known for its long stretch of mangrove beach, mudflats, and calm, reflective waters, and is frequently touted as Hong Kong's best sunset spot. It is also one of the few remaining habitats in Hong Kong that supports relatively high densities of Asian horseshoe crabs and mangrove horseshoe crabs, as well as the largest area of seagrass bed in Hong Kong.