From the Ko Mak pier in Laem Ngop (Trat)
Leelawadee Speedboats , Panan Speedboats , Suansuk Speedboat and Seatales Speedboat provide daily speedboat service to Ko Mak, with the last boat leaving for Ko Mak at 16:00. Leelawadee provides service to the Makathanee pier on Ko Mak's south shore, Panan provides service to the Ko Mak Resort pier on Ko Mak's north shore, and both Seatales and Suansuk provide service to Ao Nid Pier.
10:30am Leelawadee; 11:30am Seatales; 12:30pm Suansuk; 1pm Panan; 2pm Leelawadee; 2:30pm Seatales; 3pm Suansuk; 4pm Panan.
From the Laem Sok pier (Trat)
CP Laem Sok group  provides daily service to Ko Mak's largest pier at Ao Nid, before continuing on to Ko Kut. There was also a once-daily catamaran service between Laem Sok and Ao Nid , which has now been postponed.
Boonsiri High Speed Catamaran  or Koh Kood FantaseaCatamaran  . These two are the same, just different calling. (starting on 15 November 2013) 600 THB per person one way or 1200 baht per person incl. bus transfer from Bangkok. Pick up point in Bangkok is Khao Sarn Road and Shell Gas Station in Bang Na, at 7-8am. Sailing time between 50-60 Minutes. Departures at 2pm. daily from Laem Sok to Koh Mak(Ao Nid Pier) and Koh Kood(Bang Bao Beach), also during low season. free taxi from Trat to the pier in Laem Sok.
From Ko Chang
During the high season there are a twice daily speedboat transfers from Kai Bae Hut Speedboat at 09:00 and 11:00 to the Makathanee pier on Ko Mak. First boat is a sure bet, the 2nd only if there are enough passengers. In the low season this service won't run. On the south end of Ko Chang you can catch either a speedboat or the slower wooden boat from Bang Bao Boat. Bang Bao boats arrive at the Koh Mak Resort Pier on Koh Mak. The slower wooden boat stops at Koh Wai on the way to Koh Mak.
From Ko Kut
There is 3 boat services. One is the once-daily catamaran boat service (Boonsiri High Speed Catamaran ) running from Bang Bao Beach at 11:30, arriving at Koh Mak(Ao Nid Pier) about 30 minutes later. The other two are Kai Bae Hut Speedboat and Bang Bao Boat, providing twice-daily speedboat service (KB huts speed boats ) from most resorts that own private piers. The Kai Bae boats leave at 09:30 and 12:00, arriving at Ko Mak Makathanee Pier about 45 minutes later. The Bang Bao boats arrive at Koh Mak Resort Pier. All of these boats typically continue to Ko Chang or the mainland after docking at Koh Mak.
Ko Mak has 27 km coastline, many long sand beaches, a few hills and it is about 16 km² in area.
On low tide, it is possible to walk to Ko Kham ( privately own ), which is a smaller island less than 1 km northwest from Ko Mak. Ko Phi, also north west from Ko Mak but southwest from Ko Kham, is not occupied.
For exploring the island, scooters and bicycles are available for rent at numerous locations, and most beaches and restaurants are within easy walking distance.
There are daily speedboats from Ko Mak to the Laem Ngop on the mainland, and to Ko Chang and Ko Kut. Bang Bao Boat has one slow wooden boat to Ko Chang each day, and there is a daily Boonsiri catamaran to the Laem Sok on the mainland. The Leelawadee boats depart from the Makathanee Pier; the Panan boats depart from the Koh Mak Resort Pier; and Seatales, Suansuk and Boonsiri all depart from Ao Nid Pier.
Koh Mak to Laem Ngop: 8am Leelawadee; 8:30am Seatales; 9am Panan; 10am Suansuk; 11:30am Leelawadee; 12:30pm Seatales; 1:30pm Panan.