Try to book indigenous guides for any trekking.
Ratanakiri Top 5:
- Trekking in Virachey National Park (the more days, the better)
- Conservation International's gibbon spotting tour in the Veun Sai-Siem Pang Conservation Area
- Waterfall tour around Ban Lung (best in wet season); be sure to include Bei Srok waterfall 20km east/southeast of town toward Lumphat
- Yeak Lom Lake (easy; near Ban Lung)
- Minority villages. Try to visit ones that aren't already spoiled, if there are any left. Try hooking up with Tampuon guides around Yeak Lom lake
Mondulkiri Top 5:
- WCS gibbon- and douc-spotting project in Seima Protected Forest
- Walking with the elephants at Elephant Valley Project
- Bou Sraa waterfall well out of town; drive motorbike there
- WWF homestay and ecotourism projects 50km north of town at Dei Ey and Sre Y, in Phnom Prich wildnerness forests
- Adventure Rider Asia trail bike tours
Also some trekking and minority villages in Mondulkiri area; same rules apply as in Ratanakiri