The so-called “Back Route” from Marathon to Key West runs north up Big Spanish Channel, turns sharply west at Harbor Key Bank Light, and then skips off the northern face of a series of unhabited keys, until reaching Northwest Channel. This latter passage leads, in turn, to Key West.
We just love the “Back Route.” There’s a host of wonderful anchorages along the way, and this passage has a true backwater feeling, as if you were out in the middle of nowhere, which, for much of the route, you are.
There is one major caveat to the “Back Route.” Do NOT attempt this passage while piloting a vessel that draws more than 4 1/2 feet. There is one shallow stretch of the Big Spanish Channel that is the cause for this prohibition. Otherwise all the waters along the way have plenty of depth.

Good Morning from Key Weird,
Just wanted to let the group know that because of the strong easterly winds we have been having down here Life’s2Short took the bay side trip via Big Spanish Channel. We left Marathon at half-tide-rising and never saw less than 5.5 feet, and that was only around a small area by Cutoe Key. It was a pretty trip with the tides pushing us up Big Spanish Channel and then pushing us into Key West. The trip took about 7.5 hours going 8.5mph.
Be sure your liver is in shape before arriving here!
Todd & Brenda Lanning
Life’s2Short

Todd,
You passed through some of my favorite cruising areas in the Keys. We always pick our way in and anchor for a night or two. Cudjoe Channel to Tarpon Belly Key (take the opportunity to moon Fat Albert!), Johnston Key Channel and especially Jewfish Basin are three of our favorite stops. Try it, you’ll like it!
Regards,
Randy Pickelmann
MORNING STAR