Tam Cốc - 'three caves' in Vietnamese - is a 9km stretch of the Ngô Đồng River where limestone karst peaks rise directly from flooded rice paddies and flat-bottomed boats pass through three natural caves: Hang Cả (the largest), Hang Hai, and Hang Ba. The scenery shifts completely with the seasons: vivid green paddies in spring, the deep gold of harvest in mid-May to mid-June, lotus flowers in the surrounding lakes in June-July, and a quiet misty stillness in winter.
Tam Cốc is part of the Tràng An Scenic Landscape Complex, Vietnam's only UNESCO dual World Heritage Site. It's the more intimate and romantically scenic alternative to Tràng An - shorter boat tour, rice fields as the main character, and the kind of view that makes people understand why this corner of Ninh Bình gets compared to a painting.