I spotted this pretty spider while on vacation in Kauai, Hawaii. It was in the bushes at the entrance to Alllerton botanical gardens on the south side of the island. The web was approx 3′-5′ wide with a thicker zig-zag of silk running through the center. The spider was about 2" wide (legtip to leg tip). I’m curous what type of spider it is and what purpose the zig-zag in the web serves.
You have a type of Garden Spider from the family Argiopinae, the Agriopes. It is a close relative of our mainland species, Argiope aurantia, the Golden Orb Weaver, and could possibly be a color variation from Hawaii. The zig-zag design in the web is called the stabilimentum and it is believed to be a camouflague mechanism since the spiders often position themselves aligned with it. Here is one of our favorite websites with amazing photos of other garden spiders, including an exact double of your specimen.