Thong Nai Pan (or just TNP among backpackers) is an area on the northeastern tip of Ko Pha Ngan that includes the two beach resorts of Ao Thong Nai Pan Yai and Ao Thong Nai Pan Noi. They are maybe the most secluded but yet developed beaches on the island.
Yai means "large", and it's the larger and more developed of the two beaches. Noi means "small", and the beach here is about half the size of Yai. The two are a 15-minute hike apart from each other.
To get to either of the Thong Nai Pan beaches, you first need to make your way to Ko Pha Ngan; see the article for details.
The road to Thong Nai Pan
Once at the island's harbor of Thong Sala, there will be one or more taxi/pick up truck drivers waiting, holding up signs with the destination. Price is a fixed 300 baht/person. Note that some taxis don't go to both beaches so check for the Noi/Yai extension on their signs. Since the beaches are less traveled and quite a ride, sometimes you'll have to wait for the next boat or even the boat after that because the driver won't drive up and down for just 1 or 2 passengers. Once they do take off, the trip is about half an hour.
Since you've chosen this destination you're unlikely to be in a hurry. But if, for some reason you are and you are a little bit more adventurous, then catch a quick ride to the town (or even walk, out the harbor take a left on the main street till the round about). Here you can rent a typical Thai 125 cc motorcycle 200 baht/day or a 4x4 jeep/truck 700-1000 baht/day. But be aware that the road to these northern beaches is unpaved about half the distance and has really steep slopes, (see picture). So after one or two hours of rain, this trip can be a dangerous one for the less experienced drivers. It's about 15 km (10 mi) and it will take you around 30-40 minutes to drive.
As of May 2011, the road to Thong Nai Pan has been significantly improved. The road to Thong Nai Pan begins at Ban Tai village (on the main road between Thong Sala and Haad Rin). The road from Ban Tai to Thong Nai Pan is 13.4 km and about half of it is now sealed concrete. From the first mountain outside of Ban Tai to the Than Sadet turn off, the road is unpaved all the way and has some nasty hills with lots of dust and gravel. Once you get to the Than Sadet turn off, the road is concrete the rest of the way (7.5km) and much better. Care should still be taken as there are some deceptively sharp dusty corners. The improved road from the Than Sadet turn off to Thong Nai Pan has greatly reduced travelling times.
The sunrise, day after day.
Also try to catch a glimpse of the huge, harmless lizards that are unique to this area.
Older, mostly European men, wearing thongs, speedos and other skimpy bathing attire.
Take a walk from the one beach to the next.
Walk to the waterfalls. Noi (more beautiful but more strenuous) and Yai each have a waterfall, ask locals for directions.
Bring some good books
Yoga classes at The Yoga Studio located on Yai, en route to Wang Thong Waterfall 
Get a massage from Susie or Lee on Noi Beach.
take a walk to the viewpoint behind santhiya
Tanaporn massage house, thong nai pan noi koh phangan (behind handsome sandwich), . Professional massage and spa therapies in a beautiful thai house and garden at reasonable prices
Big Magic Tattoo (Big Magic Bamboo Tattoo), Thong Nai Pan Noi, Koh Phangan (Just off the main road behind Handsome Sandwich), ☎ +66873863474, . Get a traditional Thai bamboo tattoo. Mr Big has been doing bamboo tattoos for over 18 years and is serious about his art. Big Magic Tattoo is a relaxed space where you can discuss tattoo ideas or just hang out and have a beer.
There are ATMs in both the Noi & Yai villages and shops for purchasing souvenirs, water and snacks. There is also a big pharmacy on both beaches, and Yai has a 7-11 for picking up snacks essentials.
Karma, Thong Nai Pan Yai, has some beautiful clothing, bags and jewellery from the Northern hill tribes, India and Nepal.
Wang Thong Gallery, Thing Nai Pan Yai, sells one-of-a-kind oil and watercolour paintings and also does portraits and other custom work. 
Fresh, deliciously steamed or grilled fish. Available at a few places, usually advertising the fish by having them on display on ice in front of the restaurant.
Better Than Sex for good Thai and foreign food. They also do an excellent pizza.
Luna for great western and Thai food.
Sala, Luna's sister restaurant serving excellent sandwiches. Only open for lunch.
Me'n'u is the signature restaurant of Rasananda serving five star modern cuisine
Rasta Baby for decent Thai and foreign food.
Handsome Sandwiches for excellent 24-hour hamburgers
Flip Flop Bar on Thong Nai Pan Yai beach
Dolphin for great western breakfast, lunch and early evening tapas.
Chai Ya Bar & Restaurant for good Thai food.
Under Sky Restaurant has excellent seafood and traditional Thai dishes.
Try Memory Bar, which is just off the main road through the village, near the Nu Bar. Best home cooked Thai food around-just give it a try and you wont regret it. They'll even prepare dishes not on the menu if you ask them! Shaun, UK
All places in town are very much alike; i.e. open bamboo constructions with cold beer in the fridge, Western music on the stereo and a very relaxed atmosphere. Also on the beach you can find a couple of these bars. Some of them being part of a guest house they close between 10 and 11 PM. Others can stay open til around 2am.
I Sea Bar at the far end of the beach
Indigo Gecko in the village
Easy Corner also in the village
Yai Bar on the beach
Nu Bar has Ladies' nights Wed. and Sun.
Chai Ya Bar for pool, beer, wine and cocktails.
Flip Flop, previously on Noi beach. Now on Yia next to Central Cottage
Nice Beach Resort Bar for heavenly Piña Coladas - made of freshly opened coconut and freshly pressed pineapple served at the beach. To die for.
Typical accommodation right on the beach
Accommodation in Thong Nai Pan has come a long way. There are some villa rentals in the area with private pools as well as guest houses of different ranges all along the beach plus a couple of hidden places in the village. Prices for a bungalow at the beach range, depending on the season, from 200 to 1200 baht. So drop your bags at one of the bars and start picking out the ones you'll like best. At both ends of the Ao Thong Nai Pan Noi there are some classy resorts in the splurge range. Accommodation is cheaper on Yai beach.
The village rooms will give you a more local experience so don't be afraid to go back from the beach a bit.
On Yai Beach, backpacker bungalows can be had for 300-800b/night at the following:
THONG NAI PAN ESTATE, Luxury Living. 5 bedroom villas for rent. Great view and a fantastic infinity edge pool. http://www.tnpestate.com
Candle Hut Bungalows - somewhat overpriced and poorly designed bungalows, prone to power outages.
Paradise Garden Resort
Thai Terrace Bungalows
Longtail Beach Resort
Nice Beach Resort
Havana Beach Resort
Villa Vadee - 4 Bedroom Luxury Villa with swimming pool, 500m from Thong Nai Pan Noi Beach Villa Vadde website
Sunrise Villa - Luxury 3 bedroom villa with outstanding sea views. 5 minutes walk from Thong Nai Pan Noi Sunrise Villa website
Thong Ta Pan
Baan Panburi Resort - Very lush, yet inexpensive, resort with an extremely friendly and helpful staff. Not many amenities in the cheaper rooms. Free wifi in the reception area. They are simple huts but offer great access to the beach. Great value for the money. +66-77-238-599 Baan Panburi website
Rasananda Resort and Spa - This new five star resort features 44 private villas all with swimming pools. The resort features a spa and a restaurant, Menu offering modern European cuisine.Rasananda website
Santhiya Resort and Spa, 5-star hotel, most luxury with wooden villa, private pool. Located beside Thong Nai Pai Noi Beach.
Panviman Resort, on the headland between the two beaches.
There are several Internet cafés charging steep prices for Thai standards of 3 baht/minute. There is also Wi-Fi available on both beaches (Ban Pong on Noi Beach, Indian Bar on Yai Beach) for around 150b/hr. so bring your laptop.