The town of Olowalu is so small that if you blink, you'll drive right by it without even realizing that you passed it. I like it because it reminds me of the California coast between Ventura and Carpinteria. The area is very dry by Hawaii standards. The weather is quite similar to Southern California in that there is a distinct winter rainy season with very little rain the rest of the year. Therefore, the grass dies out during the spring.
This really isn't a hike, but we made it one anyway. There is a dirt road all the way from SR 30 to the petroglyph site and it appears perfectly legal to drive to the petroglyph site. We decided to park near the market just off SR 30 and hike to the petroglyphs. The hike to the petroglyphs is about three quarters of a mile. The dirt road is straight and relatively flat.
As a bonus, from the petroglyph site, we walked around the south side of the hill and up the paved road on the east side of the hill and found a dirt road to the top of the hill. This proved to be an excellent view point for the southern end of the West Maui Mountains, along with island views of Lanai, Molokini and Kahoolawe. This little side trip is highly recommended.
WARNING! Hiking and outdoor related sports can be dangerous. Be responsible and prepare for the trip. Study the area you are entering and plan accordingly. Dress for the current and unexpected weather changes. Take plenty of water. Never go alone. Make an itinerary with your plan(s), route(s), destination(s) and expected return time. Give your itinerary to trusted family and/or friends.