BY JENNIFER BABSON

  For two days, a group of Cuban migrants was stranded on mangrove islands off the Upper Keys, surviving only on rainwater captured in cans that someone had tossed away.

  What the seven rafters didn't know was that they were in John Pennekamp Coral Reef State Park, only about a mile from the mainland.

  On Thursday morning, the balseros -- dehydrated, sunburned and a little confused -- reached the end of a perilous journey that had started 10 days before when they shoved off from Havana in a rowboat.

  The group made it to a thick nest of mangroves stretching along the shoreline in Key Largo. Then trouble began.

  ''Their boat floated away from them Tuesday night with food and water aboard, so they collected rainwater in cans they found on the mangrove island,'' said Cameron Hintzen, resident agent in charge for the Border Patrol in the Keys.

  Currents carried their rowboat some 10 miles south of where they landed. On Wednesday, the homemade vessel turned up at Harry Harris Park in Tavernier.

  The migrants, most of them laborers in their 30s, had tried wading around the mangroves. After days at sea, they apparently had no idea they had already made it as far as the Keys, Hintzen said.

  ''It's just a solid mass of trees, and there is no way of telling how far the trees stretch or what's on the other side,'' said Robert Bodner, assistant park manager at
  Pennekamp. ``If you didn't know the area, if you weren't familiar with it and were just coming here for the first time, you definitely wouldn't know there was civilization on the other side.''

  The landscape isn't unlike some areas along Cuba's northern shores, where the coast is flanked by mangroves that stretch for miles.

  Rescuers -- alerted by passing fishermen -- found the migrants early Thursday. One man had to be located by a Monroe County sheriff's helicopter after wandering off, probably in search of help.

  The men are expected to be taken today to the Krome Avenue detention center in West Miami-Dade County where they will likely be released to friends or relatives.