Naked Places on the Big Island of Hawai'i
First of all on my list are the places where you can shed your clothes without too much hassle from the public authorities or other people. While public nudity and naked sunbathing at public beaches is illegal, there are places where this law is not strictly enforced and a few where it is never enforced.
1. Kehena Black Sands Beach (milemaker 19 on Hwy 137, not far from Kalani).
2. Kalani Honau Oceanside Resort
Even if you are not a guest, you can arrange for a visit for breakfast, lunch or supper (organic buffet style). You may be able to 
use the clothing optional pool (4:pm- 11pm) by asking or by paying (or by taking tour of the new villas for sale (as a potential owner - you might be offered several amenities). There are also non-nude activities at the resort like yoga, massage, and volleyball (so that you can squeeze in a swim in the nude at the pool).3. Steam vents scenic point -- located about 5 miles from Pahoa ( less than 1 mile after turn off to Leilani Estates on Hwy 130 (near milemarker 15) is a scenic point where the road widens for off-curb
parking. Here there are natural steam vents that have created enclosed and open air saunas. One of the them is almost a perfect teepee shape and has a small entrance you must climb through, holding 4-5 people. Locals and visitors alike enjoy these usually (but not always) in the nude, and it's great on a cool evening. Sometimes gay cruising occurs, or the straight couple get in a romantic mood and tryst, but straight locals and tourists also mingle too, so be aware and courteous.
4. Beach 67 (near Wailea Bay (sometimes called Waialea) or Beach 69) is located in South Kohala area between Kawaiihae and Waikoloa. Wailea Bay Marine Preserve's two beaches are nicknamed 69 and 67 because of their identifying numbered telephone poles (not milemarkers). Beach 69 is the larger and is great for snorkeling and diving. Beach 67, on the north side of the bay, is smaller and frequented by naturists and gay men. On Hwy. #19 at Mile Marker 71, turn into Puako Village, then right onto old Puako Road.
Beach 69 is much larger and more beautiful, but it is NOT nude. You come to it first. You'll see lots of cars park at the entrance of Wailea Beach 69. To access clothing-optional Beach 67, go about 350 yards more up the roughly paved road to a higher place, then turn right onto the gravel road at telephone pole #67, drive out onward to the bluff, then hiking down to the beach. You can also park under the trees outside the fence around a private house. Nude sunbathing on the small white sand beach hidden by trees, brush.
There is no water but there is a rustic port-a-potty. So take everything you'll need.
[Partly taken from http://www.gayhawaii.com/ ]
NOTE: Never leave valuables in a parked car in a deserted place. Auto break-ins are very common everywhere in the Hawaiian islands. Some people even leave their windows open to say 'see, there's nothing worth stealing here.'
5) Honokohau Harbor and Kaloko-Honokohau Beach is located in the Kaloko-Honokohau National Historical Park on the Kona Coast, north of Honolokohau Harbor off of Highway 19. The north end of this yellow sand beach is a popular gay beach. Privacy is difficult to find here, and Federal Park rangers often patrol to enforce a ban on nude sunbathing. However, with its warm climate and good snorkeling, this remains a very popular nude beach. Go inside the harbor/marina driveway, turn right at first intersection, go 250 yards, park inside the free parking lot, and walk into the Park via the side gate. When you reach the beach, follow to far right. [Taken partly from http://gohawaii.about.com]
You can also get a boat rides for whale and dolphin viewing as well as diving/snorkeling with giant manta rays from this harbor.
NOTE: By the way, you can always get naked at deserted spots almost anywhere on the Big Island - there are plenty of places to hike up lava-coated hills or down the shoreline and find a nice quiet place to get naked - but do so with discretion.There are a lot of such hiking spots along Hwy 19 between Kailua Kona and North Kohala. In Puna (Pahoa area), you can do so at spots along the coastal highway, Hwy 137 (Kapoho-Kalapana Road or 'red road' as it is still called locally), such as MacKenzie Beach Park.
At times, I've been naked at some of my favorite spots below:
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Other Sightseeing Spots
Of course, 1 - 5 above are some of my favorite places (because I can get naked in nature), but there are tons of other spots too.
6. Kapoho tidal pools (Hwy 132, turn right onto 137, take Kapoho Kai St into residential area, bear left to reach Wai Opai warm tidal ponds, great snorkeling spot, beware of sharp and slippery rocks, however,
There is a hot springs-fed tidal pool in a small park about 1/2 mile further down Hwy 136, Ahalanui Park, if you don't have time to snorkel.]
7. Volcanoes National Park - Viewing the Kilauea Crater, walking through lava tubes, and seeing
the current lava flows (under the guidance of park rangers)
8. Kalapana lava flow area (where it's possible to hike out near the current point where the lava flows into the ocean - but also highly hazardous). Access it from the near the intersection of Hwy 130 and Hwy 137 (coastal road).
9. Laupahoehoe Point (a county park, site of a tidal wave disaster in 1960s, and very beautiful beach park (with camping - by permit). Descend from mark entrance on the north side of Laupahoehoe Gulch (a couple of miles north of the town) on Hwy
19 about 25 miles north of Hilo.
Of course, you may want to stop at Akaka Falls on your way north out of Hilo.10. Waipio Valley (great view, fairly strenuous hike back up). I (and I have seen other) people get naked in the far beach once you've descended to the valley
floor.)Honoka'a Town is a quaint little stop with and nice eatery or two (good place to stop on your way back from hiking Waipio)
11. Waimea (Town) - nice stop for refreshments and couple of cool shops
12. Hawi and Kapa'a small towns in North Kohala - Hawi has nice art boutiques and historical sites, I highly recommend Sushi Rock (cafe/restaurant). There are also nice lookout point at the 
far north tip of the island.13. World-Class Beaches along Kona-Kohala coast -- Spencer Beach Park is a good place to stop for a swim or shower (or picnic/bbq),
Hapuna Beach, Mauan Kea Beach, Waikolao In some case, they appear to be private, but just being dominated by the big resorts. Citizens have access right to the public beaches ocated inside (almost anywhere in Hawaii) - so don't hesitate to drive in and tell them you are going to the beach. They can be crowded and full of tourists but they are worth seeing.
Puako, the Big Island's best spot for snorkeling and viewing turtles, tropical fish species, and coral is the Puako coastline. Just stop at any public access point along Puako Road found in between the multi-million dollar homes. Be careful when entering the water, as it can be tricky. You won't have to go far to see sea life, and it's also a great sport for scuba diving, too, from shore.14. If you have time, then a drive around the southern tip of the
Big Island makes a wonderful trip. Some people enjoy visiting Green Sand Beach at Ka Lae, (South Point), the most southern point in the USA. There are great sites along the route. However, traffic can get bad when you reach populated areas in south Kona because it's only a two-lane highway, so plan ahead. An alternate route is to take the Saddle Back Road from Kona to Hilo via the moutain road that passes over the hump between the two main mountains, Mauna Kea and Mauna Loa. It's great if you traveling at sunset (or sunrise).
