Here's the thing about Koh Larn: the best parts are free or close to it. The sea, the sand, the viewpoints, a dawn swim — none of that costs anything. What adds up is the optional layer: loungers, watersports, beachfront seafood at island prices, ATM fees and charter transport. Trim those and a full island day comes in comfortably under 500 baht per person.

A sample under-500฿ day

  • Ferry return: ~80฿ (about 40฿ each way on the public boat).
  • Songthaew to a beach and back: ~60–100฿ on the shared routes.
  • Lunch: ~80–150฿ at a village noodle/rice shop or a modest beachfront plate.
  • Water & snacks bought at the 7-Eleven: ~50฿.
  • Swimming, viewpoints, the beach itself: free.
  • Running total: roughly 270–380฿ — with room to spare.

Where the money leaks

  • ATM fees: Thai machines charge foreign cards ~150฿ per withdrawal. Withdraw on the mainland before you cross.
  • Charters: a private songthaew or speedboat is convenient but pricey — use shared songthaews.
  • Watersports: parasailing and jet skis are fun but short and dear. Skip them or pick one cheap thrill (a banana boat).
  • Loungers: often free if you eat or drink at the attached restaurant — just ask first.

Budget rules that actually work

Tip: Bring your own water, snacks and snorkel mask; eat in Na Baan village rather than only beachfront tables; take shared songthaews; and carry enough cash so you never need an island ATM. That's the whole game.

Do all that and you'll have a full, genuinely good day by the sea for less than the cost of a couple of cocktails back in Pattaya. For more, see our budget shortlist.