Ton Sai is a beach in Krabi Province, Thailand, offering a combination of inexpensive accommodation and great rock climbing routes that make it popular with both backpackers and climbers alike. Compared to neighbouring Rai Leh and Ao Nang it's relatively rough around on the edges; in particular, the beach gets unsuitable for swimming and becomes quite rocky as the tide goes out. But this only happens for about ten days every moon period. The rest of the time the beach is suitable for swimming.
There's no easy overland access to Ton Sai, so all visitors arrive by boat. There is however a difficult trek that will take 1.5 hours from Ao Nang, but its not recommended when you are carrying luggage, and people using this route are regularly attacked by gangs of wild monkeys. There is a half-hour trail from east Rai Leh, also not recommended when carrying luggage, but without gangs of wild monkeys to worry about. At low tide, there is a somewhat difficult scramble between the north end of West Rail Leh Beach through to Ton Sai's easternmost stretch of beach. Rai Leh is a five minute longtail ride, necessary at high tide, while longtails from Ao Nang to Rai Leh will also stop at Ton Sai. Boats between Ton Sai and Rai Leh generally don't run at night.
If you're arriving at Krabi bus station you will need to get a songthaew to Ao Nang Beach. The daytime price is 60 baht. From Ao Nang, share or charter a boat to Ton Sai. Boats run frequently from Ao Nang Beach to Ton Sai. But only when enough people have gathered and the boat is full with 10-12 persons. In high season it takes around 20 minutes to fill a boat depending on the time of the day. In low season it usually takes longer. Tickets cost 100 baht at the ticket kiosk at the east end of Ao Nang Beach, where Ao Nang Rd first meets the beach; at the west end of Ao Nang Beach; or at the Wan Sai Restaurant on Nopparat Thara Beach (east end). The price almost doubles after 18:00.
Alternatively, hire a boat and make a deal with the boatman. Expect to pay the price of 10 tickets if you want the boat all by yourself.
The boat ride from Ao Nang Beach to Ton Sai takes 10 minutes and is very scenic.
There are three ways to move between Rai Leh and Ton Sai on foot:
1) At low tide you can walk around the rocky outcrop which separates Ton Sai from Rai Leh (20 min).
2) At high tide, go to the south end of Ton Sai Beach, walk the obvious path at the end of the beach, through the forest, up and over the rocky outcrop. You'll pop out on the north side of Rai Leh West (20 min).
3) The least-used option is a longer trail through the jungle. Walk away from the Ton Sai Beach along the road where all the bungalows and resorts are. When you get to Wee's Climbing School turn (east) and continue on the road up hill. Eventually you'll pass all the bungalows. Continue on the path and you will eventually pop out on Rai Leh East near the Diamond Cave area (50 min). Although longer, this trail is smoother and easier to walk than the shorter one.
None of these options is possible at night without a flashlight/torch, and the jungle paths can be slippery and treacherous after the rain.
Alternatively hire a kayak and sail around (10 min).