The Mississippi portion of the Gulf Intracoastal Waterway (GICW) has its beginning near the eastern point of Petit Bois Island, MS near (MM "111.1 EHL") at 30°15.042’ N / 88°23.666’ W in Mississippi Sound.
This section of the GICW runs generally in a westerly direction for 70.1 miles ending at 30°09.4’ N / 89°30.5’ W (MM "41.0 EHL") in Lake Borgne, MS, 2.0 miles SE from the mouth of the Pearl River at the Louisiana State line.
Mississippi’s GICW is marked with your standard Aids to Navigation which also display yellow triangles or yellow squares. When westbound along Mississippi’s Gulf Intracoastal Waterway, marks displaying yellow triangles should be kept on your starboard hand and those marked with yellow squares should be kept to port.
While typically the yellow triangles will be found on red markers and yellow squares are found on green markers, caution should be exercised in Mississippi Sound where the GICW intersects or coincides with the Pascagoula Main Ship Channel, the Biloxi Bay Entrance Channel, and the Gulfport Sound Channel, marked by the Lateral Buoyage System.
NOAA chart coverage of this portion of the GICW beginning at mile marker "111.1 EHL" to mile marker "41.0 EHL" is provided by charts #11374, #11372, and #11367. These charts can be viewed by clicking on the links below:
All distances along the Mississippi's Gulf Intracoastal Waterway are in statute miles unless otherwise noted. Statute miles are used in order to conform to the distances shown on the small craft charts typically used along this route.
The Mississippi portion of the GICW, between the Alabama State line and the Louisiana State line, is measured based on decreasing mileage (East of Harvey Lock - EHL) from (MM “111.1 EHL”) to (MM "41.0 EHL".)
The Federal project depth for this section of the Gulf Intracoastal Waterway provides for a channel depth of 12 feet. Even though every effort is made to maintain the project depth, the actual controlling depths in the channels may vary due to shoaling reducing the available water depth until maintenance dredging can be accomplished.
Note: This is the only state on the entire Intracoastal Waterway System (AICW, GICW, or GIWW) where the waterway is not crossed by either bridges or overhead power Lines.
Tidal ranges are small along Mississippi’s coast line. Under normal conditions the mean range of tide averages around 1.5’ at Pascagoula and decreases to about 0.75’ in the vicinity of Biloxi and Gulfport. The tidal range then increases back to about 1.1’ in the vicinity of the Pearl River and the Louisiana State line.
The type of tide experienced in this area is commonly referred to as a "Diurnal Tide" - exhibiting (1) high tide and (1) low tide each day.
There are approximately (5) Entrances, Inlets, or Passes between the Gulf of Mexico and Mississippi’s Gulf Coast between Petit Bois Island in the east and Cat Island in the west. All provide access to the sheltered inland waters of Mississippi Sound as well as access to the Gulf Intracoastal Waterway.
While some of these are only suitable with local knowledge, some can be considered navigable for most vessels. We have listed them on the next page along with useful information on each to aid you in deciding if you wish to use a particular inlet.
Pass Marianne located 3.0 NM west of West Point on Cat Island. The mariner should use extra caution in this area between (MM "55.0 EHL") and (MM "65.0 EHL") of the Gulf Intracoastal Waterway. The area is subject to shoaling and frequent change.