Trang Province (Koh Kradan, Koh Muk, Koh Libong)

Trang’s small, laid-back islands lie off a quiet mainland coast with minimal heavy industry and limited traffic, a winning combo for cleaner air in Feb–Mar. Koh Kradan’s open exposure to the Andaman and Koh Muk’s wide bays invite constant airflow, while seagrass meadows around Koh Libong add to the pristine feel. Expect some diesel smells around Trang Pier or Pak Meng on transfer days, but once you’re on-island, PM2.5 typically remains low thanks to steady sea winds. Mornings tend to be the crispest for kayaking and snorkeling, and evenings are great for beach walks under clear skies. For the cleanest experience, choose beachfront stays away from busy village centers. If you plan a mainland stop, head to Hat Chao Mai National Park for coastal trails where the breeze funnels inland.