Shaped like a long bone, Molokai is only about 10 mi wide on average, and four times that long. The north shore thrusts up from the sea to form the tallest sea-cliffs on Earth, while the south shore slides almost flat into the water, then fans out to form the largest shallow-water reef system in the United States. Surprisingly, the highest point on Molokai rises only to about 4,000 feet.