From Surat Thani[edit]
If you're coming from the south, you can take a ferry from Surat Thani on the mainland with a travel time of around 3 hr for the morning ferry, or from Ko Samui, 1.5 hr, or Ko Pha Ngan 1 hr. If you're taking a boat from Surat Thani, one possibility might be an overnight ferry. These depart around 23:00 and arrive in the morning, about 06:00 (subject to changes). It's advisable to arrive early to grab a mattress. As most of the boats are formerly cargo boats the passenger facilities are basic.
From the other islands[edit]
You can also day trip on diving charters from Ko Samui. Many have high-speed boats that can make the trip to Ko Tao in about 1 hr.
Lomprayah High Speed Catamaran or Seatran are the fastest and most comfortable way to get to Ko Tao. They run twice a day from Ko Samui, Ko Pha Ngan, Surat Thani, and Chumphon. They also have online booking, seful for checking availability at peak times and all their boats have air conditioning and movies for passengers.