Below, you will find a very interesting and informative discussion, which I copied from the Trawlers and Trawlering list, concerning the relative attributes of cruising the Florida Keys by way of the Inside/ICW route, vs Hawk Channel. There are many good points to consider.

I'm planning a Christmas trip from the Miami area down the Keys probably to Boot Key and back; I have only previously run the Hawk Channel route. Can any listees provide some guidance on depth issues in ICW along this route, and mention any areas less than 5' ( I draw 4'  with twins) so a bit of a margin is nice. Does the Ceasar Creek route provide 5' on the bay side in and out? What tide range can be expected? If a strong norther sets in, how does that effect the water levels? FYI, I need 19' air draft for any bridges.  Appreciate any advise on list or direct.
Tom

Tom,
We were based out of the Keys for 10 years. I would suggest you use the Hawk Channel route since there are no advantages to the Bayside route of the ICW and even with 4 foot draft you are probably going to run aground and this could be on coral and not just sand. December as with most winter months will give you the strong winds from the north, another reason to use Oceanside. The tides are normally 2 to 3 feet but winds and celestial influences can not be overlooked. Hawks channel has plenty of water and not much to worry about and can even be sailed at night if you know the area.
Chuck

I disagree, i think the bay side as a lot to offer and with 4' draft you will have plenty of water to enjoy the many anchorages, remote spots and the sheltered water of Florida Bay.
I've done the route many times with my 4' draft hatt., the ICW is very well marked and foolproof.  no way to run aground there!  It's really mostly 6'  deep except a couple of 5'+ spots north of Key Largo. one at the entrance to Dusenberry Creek, another one of R58 off Rock Harbor, and another one just east of Cross Bank, but again, all over 5'.   Earlier this year, I took a larger boat down with a 5' draft and it was a little closer, we churned the bottom a few times but never touched.
The only reason I'd consider taking Hawk Channel is if you're running on plane as rolling wont' be an issue…  if you're going to do it slow, enjoy the bay.
And while indeed northerly winds can lower the water a bit,  the tides on the bay side are minimal, under 1'.  2 to 3' tides are outside, not inside.
Pascal

I have made the trip many times with 4 ft plus draft. It will get skinny,  but, you can make it . It's just pretty scarry at first because you can see the bottom, and it get skinny down by islamorada. You will make it fine.
See you in  Paradise!
Capt. Sterling

Skinwalker with its 4.5 foot draft and crew has traveled both sides of the Keys in the winter enough to far prefer the inside with its clear protective water and anchorages.  We do watch our depths through the few coral cuts on the inside ICW route, but even those are usually, but not always non-events for some; yet we have never had a problem or run aground in the channel.  I suggest your decision be developed on what you wish to experience.  On the inside are wonderful blissful anchorages that provide access to the edge of the Everglades by dinghy or Tour, with hundreds of small Mangrove Islands, creeks and even a few Mangrove tunnels, all  pregnant with wild life.  There is also direct access, to a number of wonderfully funky, Keys, tiki bars with a fauna all there own.  I could start naming them up and down the interior of the Keys, but they are so much more fun when one discovers them on their own. If you like exploring the water and its edges–you will like doing it from the inside of the Keys.
Bones
aka Wayne & Lynn Flatt
MV Skinwalker