Cruising/Navigating the GIWW in Alabama

Perdido Key, AL to Dauphin Island, AL

The Alabama portion of the Gulf Intracoastal Waterway (GICW) has its beginning near the eastern point of Ono Island, AL at (MM "170.0") at 30°18.6’N / 87°27.3’W.

From this point, the Alabama section of the GICW runs generally in a westerly direction for 58.9 miles ending at 30°15.0’N / 88°23.5’W (MM "111.1") in Mississippi Sound about 3.0 NM NNE of Petit Bois Island’s eastern tip.



Alabama’s GICW is marked with your standard Aids to Navigation. In addition they display yellow triangles or yellow squares. When westbound along this section of the 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 around Mobile Bay where the GICW intersects or coincides with channels marked by the Lateral Buoyage System.


NOAA chart coverage of this portion of the GICW beginning at mile marker “170.0 EHL” to mile marker “111.1 EHL” is provided by charts #11378 and #11374. These charts can be viewed by clicking on the links below:

Chart #11378 - Santa Rosa Sound to Dauphin Island
Chart #11374 - Dauphin Island to Dog Keys Pass

Distances and Mileages

All distances along the Alabama Gulf Intracoastal Waterway are given 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.

This portion of the GICW between Ono Island and just north of Petit Bois Pass (Alabama / Mississippi State Line) is measured based on decreasing mileage (East of Harvey Lock - EHL) from (MM “170.0 EHL”) to (MM "111.1 EHL".)


The Federal Project Depth for this portion of the Gulf Intracoastal Waterway provides for a channel depth of 12 feet. While every effort is made to maintain this 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.


Found along the shores of the Alabama Intracoastal Waterway

Bridges, Locks, & Overhead Power Lines


At last count, a total of 3 bridges cross the Gulf Intracoastal Waterway between Perdido Key and Dauphin Island, AL. The fixed bridges along this route provide a minimum vertical clearance of 73’.

This list is believed to be accurate as of July 2020. If any errors or omissions are noted, please e-mail us at with any corrections or recommendations.

Gulf Intracoastal Waterway Bridges - Alabama (GIWW)

Mile Marker Bridge Charted Vert. Clear. Schedule Restrictions VHF
158.7 EHL Foley Beach Expressway Bridge 73’ Fixed Bridge    
154.9 EHL Gulf Shores Bridge 73’ Fixed Bridge    
127.8 EHL Dauphin Island Bridge 83’ Fixed Bridge 93’ at Center  

The table above lists the bridges, their schedules, and restrictions along Alabama's Gulf Intracoastal Waterway from Ono Island, FL west to Dauphin Island, AL.

This bridge operating schedule can be downloaded for your personal and private use as a ZIP file. The file contains the schedule in Adobe (.pdf) file format.

Alabama Gulf Intracoastal Waterway Bridge Schedule - Download

GICW/GIWW Bridge and Lock Schedule (Florida to Texas) - Download



Overhead Cable and Power Lines

The minimum authorized clearance of overhead cables crossing this section of the GICW is 93 feet and is found at (3) locations along the Alabama GICW: (MM “158.2 EHL”), (MM “154.7 EHL”), and (MM “127.7 EHL”).

Caution - Many of the overhead cables over the waterway carry high voltage, and an extra margin of safety should be allowed when the weather is threatening.


Tidal ranges are fairly small along Alabama’s coast. Under normal conditions the mean range of tide averages slightly more than 0.5’ at Perdido Pass and increases to a little more than 1.2’ at the western end of Dauphin Island.

The type of tide experienced in this area is typically a "Diurnal Tide" - exhibiting (1) high tide and (1) low tide each day.

Entrances, Inlets, and Passes

There are (3) Entrances, Inlets, or Passes between between the deep waters of the Gulf of Mexico and this section of Alabama’s coastline. Most provide access to sheltered inland waters and access to the Gulf Intracoastal Waterway.

Open Down Arrow GIWW - Alabama Entrances, Inlets, and Passes
Perdido Key to Dauphin Island

Perdido Pass

Found 27.7 NM ENE of the entrance to Mobile Bay. The Perdido Pass enters between Florida Point on the east and Alabama Point on the west. It allows access to Orange Beach, Ono Island, Caswell, AL, and the GIWW.

The approach is marked by buoy (RW "PP" Mo (A)) equipped with an AIS Transponder lying less than 1 NM off of the outer ends of the jetties.

The pass is protected by jetties on the east and west sides of the entrance. Over half of the east jetty is submerged at low tide, caution is advised. The pass itself is well marked by lighted beacons just inside the jetties and lighted and unlighted buoys and beacons for the remainder of the pass and adjacent channels. A fixed bridge crosses the head of the pass with (2) spans available. The Cotton Bayou Channel has a vertical clearance of 41 feet and the Perdido Channel offers a clearance of 54 feet. The controlling depth in the pass was 5.5 feet the width of the channel with deeper water reported mid-channel.

Intersection with the GIWW lies 3.83 NM above the entrance at MM "166.8 EHL" near Bear Point.

Tides and Currents – Tidal Range 0.8 feet at the pass.

Little Lagoon Inlet

Lying about 15 miles east of Mobile Point, this is a small inlet protected by jetties. It connects Little Lagoon with the Gulf of Mexico. It was reported that the east jetty has partially collapsed and about 40 feet of the seaward end covers at low water. In 1985, the reported controlling depth through the opening was 1.5 feet. A footbridge, a fixed highway bridge, and a pipeline with a least clearance of 7.5 feet cross the opening. It is reported that the inlet is no longer navigable. There is no access to the Gulf Intracoastal Waterway through Little Lagoon Inlet.

Mobile Bay Entrance

Found 40 miles west of Pensacola, FL and 90 miles northeast of South Pass, Mississippi River, is the Mobile Bay Entrance lying between Dauphine Island to the west and Mobile Point to the east. It provides easy access to Dauphine Island, the Gulf Intracoastal Waterway, Mobile, AL, and to the Alabama and Tombigbee Rivers.

The approach to the entrance is marked by buoy (RW "M" Mo (A) at 30°07’31"N / 88°04’07"W); lying 1 NM SSW of the marked entrance channel.

Prominent on the approach is Mobile Point Light (Fl 10s 125ft 14m at 30°13’41"N., 88°01’27"W.), is shown from a skeleton tower on Mobile Point, the landmark 131-foot black conical tower (30°11.3’N., 88°03.0’W.), which was the base for the former Sand Island Light lying 2.5 NM SSW of Mobile Point, and Fort Morgan’s pentagon shaped brick walls are easily noticed.

The entrance is 2.8 NM wide between Mobile Point on the east and Pelican Point on the west. Pelican Bay on the west side of the entrance and having depths of 7 to 12 feet is passable with local knowledge, but most vessels will prefer to follow the dredged channel rather than chance passage between the breakers and shoals. Vessels should approach Mobile Bay through the prescribed Safety Fairways.

The main channel leads from the Gulf of Mexico and across the bar, just west of Mobile Point. The federal project depth is 47 feet. The channel is well marked by lighted buoys and ranges. Inside the bar, depths in the channel increase to as much as 56 feet.

The channel intersects the GIWW 2.7 NM above the entrance at approximately MM "133.5 EHL " near buoy (G " 25" Fl G 4s) and (R " 26" Fl (2) R 5s).

Cautions – The Coast Guard advises vessels exercise caution where the channel intersects the GIWW. Situations resulting in collisions, groundings, and close quarters passing have been reported. The Coast Guard has requested vessels make a SECURITE call on VHF-FM channel 13 prior to crossing the Intracoastal Waterway, particularly during periods of restricted visibility.

Dangers – Shoals extend about 4.5 miles S and W of Mobile Bay entrance. Southeast Shoal, covered 3 feet, is on the E side of the Bar Channel, and Sand Island Shoal, covered 1 foot, and West Bank, covered 3 feet, are on the W side.

—The wreck of the MAGNOLIA is on the east side of the channel, 0.6 NM SSW of Mobile Point near buoy (R "16" Fl R 4s).

—The wreck of the Civil War vessel " Tecumseh" is just north of Mobile Point Light in 30°13’47.5" N / 88°01’37.5"W. The wreck is marked by a buoy. The vessel is reported to be in an unstable condition, and ammunition and powder aboard the wreck could be detonated if the vessel shifts. Mariners are cautioned not to anchor in the area of the buoy and to reduce speed producing as little wake as possible when transiting Mobile Channel between Buoys "15" and "17."

Tides and Currents – Tidal range is small, averaging 1.2 feet at Mobile Point. The tidal current near the outer end of the main channel is rotary. Strong winds have considerable effect in modifying the times and velocities of the current. It has been reported that velocities of 8 to 10 knots have been observed in the Bar Channel and Mobile Bay Channel on the ebb after protracted periods of strong south winds.

Petit Bois Pass

Petit Bois Pass is used primarily by fishing vessels with local knowledge drawing about 6 feet or less. It provides access to the Gulf Intracoastal Waterway and Bayou La Batre, AL

The buoys in Petit Bois Pass are not charted due to continual shoaling which requires their frequent relocation. Mariners are advised to use local knowledge to safely transit the pass. Passage can generally be made by following the deep green water during calm weather and by avoiding the breakers during rough weather. The chart and knowledge of local conditions are the best guides. The GIWW is intersected 1.9 NM above the pass at approximately MM "112.2 EHL" near and west of lighted beacon (Q G 17ft 3M "5").

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