Wednesday, February 02, 2011


Boot Key Harbor, Marathon, FL
34 42.54 N 081 05.58 W

Naturally enough, the ICW gets a lot of mention in this blog.  However a west coast reader Diane asks, "I'm not familiar with the ICW. Where it officially begins, ends, passes thru, how much open ocean there is between, etc., could you give more details on it? Wider in some areas, swampy, flowing currents, alligators, snakes?"  That's a great topic; the kind I can my teeth into.

The actual extent and history of  the ICW is subject to definition.  Some define it as the stretch between Brownsville, Texas to Portland, Maine.   Some peg the origin in 1919, others say it was mostly a WWII effort to provide a route for shipping war materials that was immune to attack by German submarines.   In this post, I'll limit myself to the best known part, the so-called AICW from so-called mile 0 in Norfolk, Virginia to mile 1243 in Key West.  (Boot Key is at mile 1195).

First and foremost, the AICW is mostly natural.   For some mysterious reason, the coasts here are separated from the sea by a nearly continuous series of barrier islands.  The gaps between the islands form the inlets.  I say mysterious because I can't find the scientific explanation why they are lasting.   I would think that either the islands would erode away and disappear, or that the sheltered waters inside the barrier would silt in and become fast land.  I've been asking about the explanation but I haven't yet heard a satisfactory answer.  It's truly remarkable, and as far as I know, unique on this planet (If there are others, I'd love to hear about them.)

Inside the barriers, is a series of rivers, bays, sounds, and salt marshes.   The width of the barrier varies from 3-4 miles to as little as 100 yards.  The width of the wetlands behind the barrier varies from about 0.5 - to 50 miles.    Of the 1243 AICW miles, I estimate that 65% is naturally navigable, 25% is navigable with the help of dredging by the Corps of Engineers, and 10% is man-made canals.

For cruisers, the appeal of the AICW is threefold.

  1. It provides shelter from the sea.  It is possible to travel the entire 1243 miles without ever being exposed to unimpeded ocean swells.   If your migratory voyage is months in duration, then it necessarily includes periods of bad weather.   The ICW provides you with an all weather safe environment.  There are hundreds of all weather anchorages and thousands of fair weather anchorages.
  2. It makes it possible to travel long distances while getting a chance to sleep every night.   We met people who made it all the way from Cincinnati, Ohio to The Bahamas, who have never sailed in the dark.  That's not our goal on Tarwathie, but it is essential to many cruisers.  In any case, it is amazing that it's possible at all.
  3. It provides a tour of small town Americana, comparable to the famous old route 66 in the American west.    There are countless interesting places to stop and explore.  The AICW directly intersects only three big cities -- Norfolk, Charleston, and Lauderdale/Miami.

Miles 8-200 of the ICW are in fresh or brackish water, mostly North Carolina.  This water has so much tannin that it is stained brown.  There are no noticeable tides.  All the rest is salt water and tidal.  The tides vary greatly.  In Georgia, they can be more than 8 feet.  On the Indian River in Florida, they are one foot or less.   Tidal currents, more than the tidal levels are important. I've written much about those currents; they are a major consideration for ICW cruisers.  People like ourselves, with decades of inland sailing experiences, are surprised, caught off guard, and amazed at tidal currents.   We had to retrain ourselves, and to avoid disaster while we were learning.

The nature and wildlife on the AICW is wonderful.    Manatees and dolphins are native along the entire extent, although most plentiful in Florida.   We've seen alligators as far north as Myrtle Beach, SC.  Wonderful birds are everywhere.   Our favorites are the white pelicans and (you may be surprised) the turkey vultures.   Fishing is good everywhere, but having so many states with so many fishing license laws is an impediment for cruisers.

The foliage also varies greatly, adding excitement to the passage south.  Miles 0-400 are dominated by cypress swamps.  Miles 400-775 are the salt marsh area.   I have difficulty describing the beauty of salt marshes -- you have to see it yourself.  Miles 775-950 are a sub-tropical transition region with several very beautiful sections.  From 950-south mangroves are the dominant foliage visible from the water. Mangroves have their own beauty (mostly close up) but they are very monotonous.

Mile 1018 to 1089 is densely populated.  I would call it urban.  It has few anchorages, and copious draw bridges reluctant to open.  We've never traveled that whole stretch, electing to go on the outside instead.  Our first year, we did travel on the inside from Lauderdale to Miami; we swore we'd never do it again.  However, you can come back in at Government Cut, and anchor behind Miami Beach; that's a fun experience.

Mile 1089 is Government Cut in Miami and also the entrance to Biscayne Bay.  The Bay is beautiful, and makes for outstanding day sailing.  However, at that point you must make a choice.  If you draw more than 4.5 feet, you must go on the Ocean Side to the Hawk Channel to sail on to the keys.  If you have a shallow draft, you can use the inside route on the Florida Bay side.

The fun we've been having on the East Coast and Bahamas, of which the AICW is a major part, have robbed us of the ambition to sail to distant and exotic places.  It is so nice here, and there are so many places we still haven't explored.   It has to be one of the best cruising areas in the world.

Thanks for the inspiration Diane.


  1. Thanks Dick for the nice descriptive tour. So many places to cruise and visit. Need to engage in quantam jumping to experience it all.

    Having a good boat is key to enjoying the experiences. We Westsailors are definitely fortunate there!

  2. Here's a link to a description of where the barrier islands come from. They do migrate inland, but slowly.


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