VISA: A visa is required only for those visitors who are staying more than 30 days in the country. CURRENCY: The Thai currency is known as the baht. Foreign currencies and traveler's checks are easily changed at banks, hotels or money changers. Most hotels and restaurants will accept major credit cards. TIME ZONE: Thailand is seven hours ahead of Greenwich Mean Time. ELECTRICITY: In Thailand 220 volts, 50 Hz is standard, so pack those converters. Most live-aboards have both 220V/50 Hz and 110V/60 Hz available. HEALTH: Thailand's medical services and hospitals are excellent in all the major towns and quite reasonably priced. Most of the country is free of malaria and cholera, but it can't hurt to be up-to-date with vaccinations. Drinking only bottled water and using normal discretion with food will keep you and your system regular and trouble-free. LANGUAGE: The locals all speak, of course, Thai. Any attempt to speak Thai is looked upon with much gratitude. For those of us who have enough trouble with English, you will find it workable to convey most of your inquiries in our Western tongue. Try to use as few colloquialisms as possible, speak clearly and slowly and look happy. A single smile will be returned tenfold. DRESS CODE: Light, loose clothing is your best bet. Shorts and T-shirts are acceptable in most places you go in Thailand. Some of the upscale restaurants may require pants and shirts. This is also true in a few of the temple areas and the Kings Palace in Bangkok. Sweaters are good for evenings in the cool season, when visiting some of the mountainous areas and for those live-aboards that crank up the air conditioning.TEMPERATURE AND CLIMATE: Thailand's lowland climate ranges from warm to hot. Air temperature ranges from the low 70s to the mid-90s, and it can be hot and humid at times. Water temperature is a quite pleasant 72 to 82 degrees. You may hit the odd upwelling of cooler water, but this is the exception, not the rule. Generally 80 degrees is the norm, so a dive skin or thin wetsuit is more than acceptable. Global weather seems to have taken a turn for the unpredictable as of late, so the following is only a guideline: Thailand has three seasons, which are influenced each year first by the northeast monsoons and then later by the southwest monsoons. The dry season runs November through March with the possibility of northeast monsoons toward the end of this time. Removing the extremes, you can expect pleasant weather with the occasional rain squall and good visibility underwater. April and May are the hot months. Mirror-flat seas, blisteringly hot days and an increase in plankton all occur at this time. The rainy season begins around June and runs through October. This is the time of the southwest monsoons, which bring strong winds and heavy rains. There is a break in midseason with the possibility of intermittent nice weather mixed with short rainfalls toward the end of July through August.