There are a number of Elephant Camps on Koh Chang island where you can see Asian elephants up close and go for a ride on the back of the elephant
Baan Kwan Chang Elephant Camp is one of the largest elephants camps on Koh Chang. The Bann Kwan Chang Elephant Camp is located on the northern end of Koh Chang and is part of the Asian Elephant Foundation. They can arrange to pick you up from your hotel and then take you for a 2 hour trek riding the elephants.
The Baan Kwan Chang Elephant Camp is surrounded by nice rainforest so is one of the nicest areas to go trekking.
Just ask in your hotel to contact the closes Elephant Camp on Koh Chang and they will come and pick you up from your hotel