Mae Haad Pier is the main pier in Koh Tao Island. The area is full of little shops and restaurants, so you can spend your time there while waiting for the ferry to depart. Several big companies have offices at the pier and have a daily ferry schedule to the various destinations.
Address: Mae Haad Pier, Koh Tao, Thailand
Lomprayah ticket office is located at Mae Haad Pier. When you enter the pier area you will see a big Bon voyage sign in front of you. Continue walking about a 100 meters to your right and you will see a wooden office with a green roof and a big Lomprayah sign above the entrance. There you will find the friendly staff who will show you the way to the ferry.
KP Tripadvisor also uses Lomprayah ticket counter.
Address: Mae Haad Pier, Ko Tao, Ko Pha-ngan District, Surat Thani, Thailand
Songserm Pier is located just a short walk from Mae Haad main pier. You can easily reach it by walking along the beach in a southern direction from Mae Haad pier. The Songserm office is on the beach, opposite the pier ramp with the sign "Express Boat - Pier".
Address: Songserm Pier Koh Tao, 25/1, Moo 2, Koh Tao, Surat Thani 84280, Thailand
You can find directions from your current location here: https://www.google.com/maps/dir//Mae Haad Pier, Koh Tao, Thailand