Phnom Penh has fewer obvious day trips than Siem Reap, but a couple of half-days will get you outside the city. The Killing Fields of Choeung Ek, 15 km south, are usually combined with Tuol Sleng into a single sobering morning. The Mekong island of Koh Dach (Silk Island), 30 minutes by ferry from the city, is a low-key day of silk weaving and rural cycling. The 11th-century pre-Angkorian temple of Phnom Chisor, 60 km south, is a long climb in the heat but rewarding for archaeology enthusiasts. The Phnom Tamao Wildlife Rescue Centre, also south of the city, is the most ethical animal encounter near Phnom Penh.
The riverside town of Udong, 40 km north, was Cambodia's capital before Phnom Penh and has a hilltop crowned with royal stupas and shrines — an easy and rewarding half-day for anyone interested in the country's pre-colonial history.
For anyone with more time, Kampot (3 hours south by road) and the colonial hill station of Bokor make a worthwhile overnight, as does the riverside town of Kratie (5–6 hours north) for a chance to see the freshwater Irrawaddy dolphins.
