The vast majority of travellers to Si Phan Don end up on these twin islands. Don Det (ດອນເດດ) is defined by its hippyesque party scene, though it's really quite mild and there's nothing stronger than grass in the 'happy' snacks sold openly at some bars.
Of course there's much more to these two islands. Heading south from Ban Hua Det (Hua Det Village), the guesthouses thin out and the icons of rural island life – fishermen, rice farmers, weavers, buffalo, sugar palms – are on full display. Chill in a hammock, wander aimlessly around the islands or languidly drift downstream in an inner tube in the turquoise arms of the Mekong.
The serenity continues across the French bridge on Don Khon (ດອນຄອນ), but down here there are also some gorgeous waterfalls to visit, sandy beaches to lounge on, dolphins to spot and even a little patch of wilderness to explore.