Although Koh Samui now ranks as my favorite place in the world, I really detest the transportation system, or lack thereof. The most economical, but also most life threatening, way to get around the island is a motorbike for 200 baht a day. It is safer to rent a car and that is a great choice if you have a large group or your family with you. I don’t know the prices exactly, but it think they range from 800-1000 baht. Next are the tuk tuks, which are most similar to a public bus. Since there is only one road on the island, they drive around and pick up anyone that needs a ride. Locals ride for 60 and tourists for 80. They are reluctant to go too far outside the touristy areas so tough luck if you are staying outside Chaewang or Lamai. The reason I hate tuk tuks is because at night time, they charge over 300 baht to go even a small distance. Finally taxis. Taxis in Koh Samui as far as I know just don’t have meters; I wouldn’t even bother with these as they charge a lot to go anywhere.
When you arrive in Nathon off the ferry, there will be tuk tuks waiting for you. 80 per person seems to be the standard price. If I could do it again, I would rent a motorbike near Nathon and drive to wherever myself because getting back to Nathon is a bitch. We had to return the motorbike in Maenam and catching a tuk tuk is Maenam is not that easy because it’s not a popular area and we were short on time. We paid 500, haggling down from 800, to get to Nathon by a car service since we were about the miss the last boat off the island.
Once at the ferry port, just say, “Surat Thani” and “tickets?” And you will be pointed in the right direction. Combination ferry (to Donsak) and bus (to Surat Thani) tickets are 240 baht with a total travel time of about 3 hours. Once you arrive in Surat Thani you are right next to the bus terminal, but we had missed the last bus to Krabi so we stayed with a Couchsurfer.