If you are coming from abroad, you will have to do 14 days quarantine in Bangkok first, but after that if you fly down straight to Koh Samui and directly travel to Koh Tao, there is no additional quarantine to you for you here on the island. If you come from Bangkok, you will have to quarantine on Koh Tao for 14 days. Some other red and dark red zones within Thailand require quarantine as well. Make sure you check the latest guidelines before heading down.