Missionary Bay is a large, shallow estuary at the northern end of Hinchinbrook Island National Park, forming part of the western coastline of Hinchinbrook Island. It is characterized by approximately 50 square kilometers of dense, biodiverse mangrove forests lining its shoreline, which are considered among the most diverse in Australia. The bay features a shallow subhorizontal tidal zone with extensive offshore seagrass beds. This is a remote, wilderness area with a wild and rugged character, accessible only by boat. The primary paddling experience involves navigating through the intricate mangrove systems. Access for paddlers typically requires a boat transfer from the mainland, with commercial day trips available from Cardwell via operators like Hinchinbrook Island Cruises, which transit through the mangroves of Missionary Bay en route to Ramsay Bay. A significant safety consideration is the confirmed presence of saltwater crocodiles in the area. The waters are also part of a dugong habitat. Wildlife sightings may include dugongs, turtles, dolphins, and abundant birdlife, such as the beach stone-curlew. The aesthetic is one of a pristine, natural mangrove estuary backed by the mountainous spine of Hinchinbrook Island. There are no specific facilities or amenities for paddlers detailed within the bay itself, as it is a protected national park. Camping areas exist elsewhere on the island's coastline. Paddlers should be aware that dogs are not permitted on the Thorsborne Trail, which runs along the island, indicating a general policy of strict environmental protection.