Khao Lak

Khao Lak for calm: fewer crowds, cheaper beachfront resorts, and no go-go bar scene, but also no shopping malls and limited nightlife. Phuket for infrastructure: the airport, hospitals, restaurants of every kind, and beach variety. Many families fly into Phuket and transfer straight up the coast. Divers pick Khao Lak outright because Similan boats leave from here.

It's about 70–85 km north along Highway 4, roughly 80–100 minutes by car depending on where on the strip you're staying. The airport taxi counter charges a fixed ฿1,800 a car (pre-booked transfers about ฿1,500–2,500), shared vans are ฿550–750 a seat, and most resorts arrange transfers. You don't need to go into Phuket town. The airport sits at the island's northern end, so you never have to cross Phuket itself.

The park opens roughly October 15 to May 15 and closes entirely for the monsoon. In season, day trips run daily from Thap Lamu pier (about ฿3,700–4,200 with the ฿500 park fee, lunch and snorkel gear). February to April brings the calmest seas and best visibility. Liveaboard dive boats also depart Khao Lak for multi-day Similan and Richelieu Rock itineraries.

Partly. May to October brings heavy showers, red-flag swimming days, and the Similans are closed. But Khao Sok is arguably better in the green season (full waterfalls, active wildlife), resort prices halve, and the beaches are near-empty between storms. If your trip is beach-first, come in season. If it's Khao Sok-first, I'd say the monsoon months are fine.