Nakalele Point is the most northern point Maui. It is located just past mile marker 38. You can't miss the parking area since there is usually a lunch truck parked here. Scattered across the field are numerous "cairns" or rocks piled by visitors along with natural rock formations.
The primary attraction here is the famous Nakalele Blowhole, located about 1200 foot along a clearly defined path. If the surf is heavy, or it's high tide you'll actually see the geyser effect long before you reach the blowhole. Nakalele Point itself is marked by a light beacon which you'll pass. You'll also walk past numerous tidepools along the shore and beautiful lava rock formations.
The blowhole is created when the pounding surf undercuts and wears away a shoreline lava shelf. A hole in the lava shelf causes a geyser-like effect which can reach over 100 feet when air and water are forced upwards through the hole.
While it may seen tempting to approach the blowhole for a great photo opportunity, don't do it. People have been killed as they get sucked back into the hole by the retreating water at this and other blowholes in Hawaii.
A second viewing area is less than 1/2 mile past Mile Marker #40. This is a smaller pullout and you are only a few feet from the overlook. The third overlook is a littler farther down the road where there is a larger pullout. Walk about 100 feet to this overlook. From these overlooks you'll also get a great view of Kahakuloa Head to the east.