Kaeng Krachan Dam

Kaeng Krachan Dam is an earthfill dam across the Phetchaburi River, built between 1961 and 1966 — one of the largest dams of its type in Thailand, with a crest running 760 metres long and 58 metres high, holding back a reservoir of about 710 million cubic metres. It’s free to visit and open daily 06:00-18:00, a separate stop from Kaeng Krachan National Park further up the valley, which charges its own entry fee.

The dam sits at the eastern edge of the national park — Thailand’s largest protected forest, at 2,915 square kilometres — and functions as the gateway most visitors pass through before reaching the park gate itself. You can drive straight across the dam crest for a wide view over the reservoir and the forested hills beyond, or hire a longtail boat at the jetty (roughly 500-800 THB per boat, seating 6-8) for a short run out to Monkey Island, where macaques come down to the shoreline to be fed. Downstream, the stretch of the Phetchaburi River below the dam is a popular put-in for rubber-raft floats — an easy multi-kilometre drift rather than whitewater.

Early morning is calmest, with the reservoir often glassy before the wind picks up, and a chance of low mist over the water in the cooler months (November-February). Weekends bring Bangkok day-trippers heading further into the park, so the jetty and viewpoint car park fill up from mid-morning; weekday visits are quieter.

Watch out: the dam itself charges nothing, but Kaeng Krachan National Park beyond it does — 300 THB for foreigners, 60 THB for Thai nationals — so budget separately if you’re continuing on to the park’s waterfalls or the Phanoen Thung sea-of-mist viewpoint.

Insider Tip: Time the boat trip for late afternoon rather than midday — the light is softer on the water, and the macaques on Monkey Island tend to be more active feeding before dusk.

The dam is roughly 55-58km from Phetchaburi town — drive south on Highway 4 towards Tha Yang, then follow signs onto Highway 3499 into Kaeng Krachan district. There’s parking near the dam crest and jetty and basic food stalls nearby, but little shade over most of the dam itself, so bring sun protection if you’re stopping to take photos rather than driving straight through.