White Moonflower, also called Tropical White Morning-glory, or Moon Vine, was introduced to Hawaii after being naturalized from Mexico.
This beautiful species (Ipomoea alba) has found a welcome home throughout many temperate places. In Hawaii these vine plants can be seen growing wild or planted. Their large blossom of up to about 6 inches unfurls in the evening or when in cool shade. The flower gives off a nice aroma and is beautiful when fully open.
There is more great information on this flower here.