The largest island in the Si Phan Don area, Don Khong is nowhere near as popular as the more southern islands of Don Dhet, with its chilled-out atmostphere, and Don Khon, with more activities on tap. The interior of Don Khong is almost entirely given over to rice cultivation while just about all the accommodation is crammed into and around the sleepy town of Muang Khong which is situated on the east coast of the island.
The major pastime on Don Khong is cycling around the countryside. Both in the early morning and late afternoon, this is an excellent way to pass a few hours, though it's best to avoid the middle of the day when the heat is oppressive.
There are a few small villages scattered around the island's edge along with some interesting little temples and pleasant riverside scenery, and those with the time and money could scare up a multi-day trek or two, but overall the main attraction here is the gentle pace of life.
Another option is to ride 8km west to Muang Sen where there's a marketplace and some floating restaurants with views of the setting sun.
Some of the local hotels are working on offering treks of the mountains in the interior, but to date none are running. When they do get going, expect them to be pricey