St. Andrews Sound is located on Georgias Atlantic coast at Intracoastal Waterway Mile 690. The sound separates Jekyll Island (north) and Cumberland Island (south) with the Intracoastal Waterway leading right down the middle of the sound between the two islands.
The image above is a view from the east looking west over St. Andrews Sound. To the right is the southern tip of Jekyll Island, while off to the left (south) of the inlet is the northern tip of Cumberland Island, a National Seashore and a great place to visit and explore. Most of the island used to belong to the Carnegie family, and the ruins of their great mansion, Dungeness can be toured by taking a National Park Service ferry boat from St. Marys, which is about 21 miles south from St. Andrews Sound.
Use NOAA Chart 11489.
There are two entrances to St. Andrews Sound, but the southern one is more reliable and, unlike the northenr entrance, is well-marked to guide you through the shifting shoals.
From the Atlantic Ocean, first set a course for Morse (A) buoy STA, which is located near the area of waypoint N30 55.555 W81 18.969. Once you have picked up the Morse (A) buoy, set a course to pick up green nun buoy 1 about 1.7 miles to the east. The approach channel turns north at green nun buoy 1, leading past red nun buoy 2, green nun buoy 3 and red nun buoy 5.
At green nun buoy 5, you need to set an approximate course of 329 degrees magnetic for about 1.5 miles, and then head west-northwest to intercept quick flashing red buoy 32, which is situated at ICW Mile 690. Be sure to avoid the shoals on either side of the channel once you depart green nun buoy 5. The channel is unmarked all the way to quick flashing red buoy 32, and you will see breakers on either side (visible in the image above).
Once you have cleared quick flashing red buoy 32, you can pick up the Intracoastal Waterway route north or south. The passage south leads behind Cumberland Island toward St. Marys and Fernandina Beach. The north route leads up toward Jekyll Island where marinas can be found.