Age restrictions and other laws
Thai law requires that tourists carry their original passports at all times, though sometimes it's more practical to carry a photocopy and keep the original locked in a safety deposit. Mine is scanned in, photoshop all the relevant pages together then printed business card size. It is illegal for under-18s to buy cigarettes or alcohol, to drive, or to have sex, and you must be 21 or over to be allowed into a bar or club (ID checks are often enforced in Bangkok). It is illegal for anyone to gamble in Thailand (though many do). Smoking is prohibited in all air-conditioned public buildings (including restaurants but usually excluding bars and clubs) and on air-conditioned trains, buses and planes; violators are subject to a B2000 fine. Dropping cigarette butts, littering and spitting in public places can also earn you a B2000 fine. The Thais laugh at these, calling them 'Farang (foreigner) Tax', as it's only us the police even dream of picking on. Beware, they are looking out for you, easy collar. There are fines for overstaying your visa, working without a permit, and not wearing a motorcycle helmet and violating other traffic laws.