Cambodia's water experiences are concentrated on the Tonle Sap — the world's largest seasonal lake, which doubles in size during the monsoon as the Mekong reverses the Tonle Sap River flow — and the Mekong itself. Floating village boat tours on the Tonle Sap from Siem Reap — where entire villages of 10,000 people live on the water year-round on floating platforms, navigating by boat to school, market, and hospital — are one of Southeast Asia's most unusual social and geographical experiences. Mekong River sunrise cruise from Phnom Penh to the Cambodian-Vietnamese border, where the river is at full monsoon breadth and the floating water hyacinth islands drift past, and Kampot River boat excursions through the mangrove estuary to the Gulf of Thailand coast add further options. Koh Rong island speedboat day trips and Cardamom Mountains river kayaking complete the range.