Basic
- Air tickets
- International passport
- Travel insurance
- Bank cards (with the principal amount) and money (a small amount in foreign currency).
- International driving license.
Clothes
- Clothes for a trip to Thailand need only summer and light, such that you can walk in it in 30-degree heat (in the case of a trip to the north, you can take one set of warm clothes), and you need a minimum of it.
- In the heat, you can steam up in your dark T-shirts and shorts.
- Light and light T-shirts/T-shirts are better with long sleeves.
- Shorts or skirts.
- Light trousers, dresses.
- Swimsuits and swimming trunks.
- Hats.
- Lightweight “breathable” shoes: sandals, sandals, flip-flops, etc.
- Sweatshirt, pants, warm socks.
Useful
- Medicines (smecta and rehydrone, nurofen and paracetamol, hydrogen peroxide and iodine, etc.). In Thailand, there is a pharmacy in any city, but it is better to take the most necessary things with you.
- Mosquito repellents are always useful.
- Sunscreen.
- Goggles and masks for swimming.
- Glasses for the bike.
Various
- A small kettle for tea. It is very convenient, since hot tea in cafes in Thailand is not found everywhere.
- The mains filter is an extension cord of compact size, since sometimes the voltage jumps, or there are often not enough sockets in guest houses.
- 3G modem, as mobile Internet is the most common type of Internet in Thailand.
- If you are a hiker, travel clothes and shoes.
- Not a working bank card, which you will be asked for when renting a bike to make a scan of the card instead of a deposit, or leave as a deposit.
- A cord to connect two laptops over LAN if you are traveling in a pair. It can be useful when renting a house with cable internet.
English 
Russian 
German 
Polish