6. Natural Bridge-Caverns at Natural Bridge are the deepest caverns on the East Coast and go 34 stories underground below the earth's surface to see nature's magnificent underground landscape of dripstone, flowstone, draperies, pools, stalactites, and stalagmites.
Location: Between PuÊ»upoa and Makahoa Points, Hanalei. Description: Hanalei Bay, the largest bay on KauaÊ»i, is bordered by a white sand beach approximately two miles long and 125 feet wide. The beach is located between Hanalei River to the east and Waipa River to the west.
If you look at a map it appears to be about 5 mi at it's widest and 10 mi long. Because it connects to Allen's Bay and Pike Bay one person's measurement may not equal another's. Wikipedia calls it approximately 10 mi (16 km) long and 7 mi (11 km) wide. They say the surface area is about 24.9 square miles.