Horn Island Pass is the primary navigable waterway separating Horn Island and Petit Bois Island within the Gulf Islands National Seashore off the Mississippi coast. It is also known as the Pascagoula Ship Channel, a critical designation for paddlers due to significant commercial vessel traffic. The pass is a major crossing point for paddlers traveling between the mainland and the barrier islands or between the islands themselves. A direct open-water crossing from a mainland launch, such as from Hollingsworth Point or Davis Bayou, to the pass can be approximately 9 to 10 miles. The pass itself is a defined channel with depths reported around 17 to 18 feet, marked by a series of lighted buoys including LB 11 and LB 17. Tidal currents within the pass are a primary planning factor, with maximum ebb currents exceeding 1.3 knots and flood currents around 0.9 knots; slack water periods are brief and must be timed for safer crossing. Wind exposure is significant, with conditions on the north and south sides of the islands differing drastically. The south side, facing the Gulf of Mexico, is subject to ocean swell and waves, while the north side in Mississippi Sound is generally shallower and calmer but can develop chop. Paddlers must exercise extreme caution and maintain a wide berth from the deep-draft ship channel, as large vessels including natural gas barges use this route. The surrounding wilderness islands offer boat-in camping opportunities, though groups of 10 or more require a permit from the National Park Service. Wildlife sightings commonly include dolphins and numerous seabirds like pelicans. The area is also known for the presence of Figure 8 jellyfish, and biting flies can be a severe nuisance on the islands, especially in calm conditions. Water quality can be affected by events like tropical storms, which may bring tar balls to shorelines, though cleanup crews are sometimes active.