Time for Tips

💡 SIM card: Get your SIM card directly at the airport: Real 5G is good.
💡 Transportation: Best way to get around the islands is by scooter, best way to get from island to island is by boat, best way to get from city to city is by train or plane (book trains directly on 12gosia, book boats directly at the port it's much cheaper than on 12goasia, book flights directly on the companies website but use Skyscanner, and for scooters you can ask your hotel/Airbnb to put you in touch with rental companies).
Sleeper trains are a really good way to explore the country from south to north, it's cheap (around 650baht) and a unique experience, I highly recommend it (economical way to go from Bangkok to Chiang Mai and from the southern islands to Bangkok).
💡 Good to know: In Bangkok some people may try to cheat you by telling you that the places you want to visit are closed and that they can take you to other good places, don't trust them!
💡 Others: Remember to bring a snorkelling mask, there are spots everywhere, it avoids renting one every time
Bring this bottle bag for excursions, and a waterproof bag
There are many elephant sanctuaries in Thailand, make sure you go to an ethical place, elephants must not be ridden and mistreated...