Cat Tien comprises an amazingly biodiverse area of lowland tropical rainforest. The 72,000-hectare park is one of the outstanding natural treasures in Vietnam, a true jungle, and the hiking, mountain biking and birdwatching here are the best in the south of the country. At weekends and public holidays it gets busy with domestic tourists – it's worth calling ahead to book the most popular excursions.
Fauna in the park includes 100 types of mammal including elephants, leopards, the bison-like guar, and primates such as gibbons, pygmy lorises and langurs. There are also 79 types of reptile, 41 amphibian species, plus an incredible array of snakes, spiders and insects, including 400 or so butterfly species. Of the 350-plus birds, rare species include the orange-necked partridge and Siamese fireback.
Bear in mind that the larger animals, including elephants and leopards, are very retiring. You're most likely to see primates, birds and reptiles.