Sunken Forest

From fireisland.com:

Maintained by The Fire Island National Seashore, this unique area is one of the last remaining maritime forests on the eastern seaboard. It earned its name because it appears lower than the surrounding water. The forest is not actually below sea level -- the high surrounding sand dunes that protect this environment create the illusion of being lower than sea level. The Sunken Forest spans approximately 40 acres, so there is plenty to see. You can walk for miles up and down the roller coaster boardwalks that carry you over two rows of sand dunes. The Sunken Forest consists primarily of American holly, sassafras, and shadblow. Some trees are estimated to be well over 200 years old. This naturally preserved wilderness is abundant with hardwood groves, dunes, swamps, and marshland. Serious hikers, bird watchers, and ecologists find this part of the island absolutely fascinating. With several ecosystems, there is plenty of diversity in the flora and wildlife. While walking through the forest, be sure to look up -- the twisted canopy is the forest's most intriguing attribute. The parks department provides guided tours during the summer season.