great gunk-holing in that area
The area from Marco to the Keys is jam packed with great anchorages. From Marco you can day sail to Indian Key (Everglades City entrance channel). There are about 6 great anchorages in there for even 40' boats, just have your mosquito screens up by sunset. From there it is a 30 mile sail to Little Shark River. That is big enough for a small cruise ship to anchor in (alone). You can head up the river close to 15 miles anchoring in every little tidy-hole you come by. You will end up in Oyster Bay or even White Water Bay. Huge off shore fishing boats often go in there and act as home base for the flats boats working the deep glades area. From Shark you are only 30 or so miles from Boot Key Harbor in Marathon. In your boat check out Lower Matacumbe Key Bight (bay side), great anchorage up there, lots of sea turtles that play with you in there. Depending on the winds you can snuggle right up to the everglades and hide behind one mangrove island or another if you watch the weather. Carefull of the tidal currents in the Everglades, they rip....