Accessible by a short bus ride from Kanchanaburi, Erawan National Park in Thailand features 200 square-miles of limestone hills, forests, steams, flora and fauna. Founded in 1975, its most famous feature (and justifiably so) is the seven-tiered waterfall from which the park derives its name. The waterfall itself is named after a mythological three-headed white elephant that the falls and pools are said to resemble. In any case, the waterfall is truly spectacular and the various pools into which it spills (perhaps gushes is a better word) are great for swimming.
Though incredibly popular (particularly with locals and travelers without their own means of transportation), the geography of the falls is not for the faint of heart or the physically unsound. The trail that serves as the main means of accessing the pools is steep, poorly maintained and even occasionally non-existent. Proper footwear and a healthy dose of caution come highly recommended at Erawan.
While much of the park is inaccessible to travelers without transport, the falls can be very crowded on weekends and holidays, and are reputedly overrun entirely during the Thai New Year. Trekkers in search of solitude would do well to travel elsewhere. For the rest of us, the exotic beauty and affordable recreation make it an excellent choice.
For those with private transportation, there are also four noteworthy caves dotted about the park (Mi, Rua, Wang Bahdan, and Phartat) that are worth exploring if you fancy yourself an amateur spelunker.
Naturally, accommodations inside the park are limited, but park bungalows and camping equipment are available through the park offices via reservation.