Carl Nielsen, age 12, of Indianapolis, Ind.., For his question:

What are the floating islands of Florida?

The sun swept state of Florida, has many interesting islands and waterways. In the rainy season, some of its lowlands are swampy, and only a few humps, called land islands, peep above the water. Across from the swampy everglades there are small islands called keys. The mangrave trees of the swamp spread their tangled roots through the shallow sea water to form floating islands which seem to rise and fall with the tides.

Most trees cannot live rooted in soggy soil. But the mangrove must be rooted in silty sea water. Dozens of roots dip dawn like vines from the branches and establish themselves in the tidal sea water. Silt and mud clog the tangle of roots, and when the tide is low, the mangrove tree seems to be a floating island.