By plane
Bangkok Airways (http://www.bangkokair.com) flies twice a day from Bangkok's Suvarnabhumi Airport the "new" BKK to Trat. The flights depart at 08:45 and 17:05, and take 1 hour exactly. Costs are between 1,800B and 3,300B.
Direct door-to-door minibus transfers from Trat airport to Ko Chang resorts cost 475 baht/person one way and 800 baht/person return including the ferry crossing.
From Bangkok's Suvarnabhumi Airport, take the free express shuttle bus from outside the arrivals concourse to the airport's own bus terminal, and from there the next available bus to either Trat or Chanthaburi, then proceed as described below.
By bus
From Bangkok the most economical way to get to Laem Ngop where the Ko Chang ferry piers are is to take a 1st class bus #999 from the Eastern Ekamai Bus Terminal direct to the Laem Ngop piers. The fare is 268 baht and takes just over five hours. Departures from Ekamai are at 07:45 & 09:45, and return at 14:00 and 16:00 it seems no more 4:00pm bus. Subject to seat availability, this bus can also be boarded at Chanthaburi and at Suvarnabhumi Airport. However, as of December 2009 there was a more comfortable way to travel from Bangkok Airport to Ko Chang: the new bus line # 392 starts from the airport at 07:30 and returns from Koh Chang at 12:30. Tickets can be bought online at the Suvarnabhumi Burapha Bus Company (http://www.bussuvarnabhum...). As of 1 Nov. 2010 there are also express shared minibuses running from Suvarnabhumi airport non-stop to Lonely Beach on Ko Chang (http://www.bussuvarnabhum...). Tickets are 308 baht for the big bus and 600 baht 800 baht round tripfor the Lonely Beach Express minibus which includes a ticket for the ferry.
Alternatively, there are 1st class approx. 5 hours, around 250 baht and 2nd class services from both the Eastern Bus Terminal Ekamai and Northern Bus Terminal Moh Chit direct to Trat, and frequent songthaew services from Trat to Laem Ngop approx. 30 minutes, 50 baht/person. Departures from Ekamai are more frequent than from Moh Chit. If coming by bus from the south, the #511 air-con bus can be used to connect directly between Bangkok's Southern Sai Tai Mai and Eastern Ekamai bus terminals.
Connection in Trat can also be used if coming from Pattaya 2nd class bus, 4 hours, around 200 baht.
There are direct minibus services to Laem Ngop from Pattaya, Ban Phe gateway to Ko Samet, and Bangkok's Khao San Road and Victory monument in front of the Payathai hospital. They, however, are less comfortable and spacious than public buses, and you may be charged significantly more by travel agencies selling tickets to these, as often with any tourist-oriented transportation in Thailand.
It may also be possible to proceed directly to Laem Ngop by minibus or songthaew from the Hat Lek / Koh Kong border crossing with southern Cambodia, depending on the time of year, time of day, etc - enquire locally. Price around 120 baht one way from the border to Trat bus station
By Taxi Or Limousine
From Bangkok or Suvarnabhumi international airport the ride takes a total of about 5-5.5 hours by Limousine (http://www.limousine.in.th/) or Taxi. Most taxi driver will decline this journey as the risk of empty return is too high for them. Most airport limousines or minibuses (http://www.kohchangminibu...) will deliver you at the hotel or resort on Koh Chang, especially if they can make it back to the mainland before the last ferry sails.
By ship
Most ferries operate from Laem Ngop, which has three piers . The Laem Ngop Tha Khrom Luang or Tha Laern Ngop pier is approximately 700 metres west of Laem Ngop. The Centrepoint Tha Centre Point pier is located about 3.5 km north-west of Laem Ngop. These piers serve both vehicle and passenger ferries.
Koh Chang vehicle ferry pier is located in Thammachat Bay Ao Thammachat, around 15 km west of Laem Ngop.
All piers on Ko Chang are situated on the eastern side of the island. The major piers are the two Dan Kao piers, Tha Dan Kao and Tha Ferry Dan Kao, who handles most of the traffic. To take a boat from Laem Ngop to the Dan Kao piers take around 45 minutes. The car ferry from Laem Ngop take around 1 hour and arrives at the Tha Ferry Dan Kao pier, situated 400 metres southeast of the Tha Dan Kao pier. The car ferry from Thammachat Bay stops at the Ko Chang Ferry Pier Tha Ferry Ko Chang in the Sapparot Bay Ao Sapparot, 3 kilometres northwest from the Dan Kao piers.
Light meals, fruit, fruits and beverages are available at all the piers and on the car ferries.
There are two operators that provide daily bus services from Ko Kood to Ko Chang. One is based in Ban Bao, the other on Kai Bae Beach (http://www.kohchangspeedb...) Rates are the same but departures times can vary, so make sure to book ahead.