Reboard the boat and cruise to the Pak Ou Caves. An important religious site overlooking the river at the junction of the Mekong and Ou Rivers, the revered Pak Ou Caves consist of two sacred limestone caverns filled with Buddha images of all styles and sizes, brought by devoted villagers over the centuries. The lower cave, known as Tham Ting, is entered from the river by a series of steps and can easily be seen in daylight. The higher cave, Tham Phum, is deeper and requires a torch for viewing. Continue on to the former royal capital of Luang Prabang (approximately 7 hours total journey time). This atmospheric World Heritage-listed city is a favourite of many travellers. Nestled in the hills of northern Laos on the confluence of the Mekong and Khan rivers, the city is claimed to be ‘the best preserved city in South East Asia’ by UNESCO. The city and its people retain a refined, yet relaxed, air and it’s a wonderful place to wander the streets into boutiques, cafes and small shops. Stay in a hotel tonight and if you are feeling energetic, climb Mt Phousi for some sunset views - the large hill that dominates Luang Prabang's skyline, topped by a glittering golden stupa. You can climb the 328 zig-zag steps up to the sacred gilded stupa and big drum of the Phu Si Temple for a panoramic view of Luang Prabang and its surrounds.