814km (506 miles) S of Bangkok, then 42km (26 miles) W of Krabi; 160km (99 miles) SW of Phuket
Phi Phi is in fact two islands: Phi Phi Leh and Phi Phi Don. The latter is the main barbell-shaped island whose central isthmus (the barbell handle) was hit badly by the tsunami. Ko Phi Phi is a popular choice for day trips, snorkeling, and scuba junkets from Krabi. Crowds of noisy tourists also descend upon Maya Bay, on Phi Phi Ley, where filmmakers shot the Hollywood film The Beach, with Leonardo DiCaprio. Thai students and environmentalists have long protested the amounts of rubbish left by these tour groups. (Note: Day-trippers should dispose of trash after arriving back onto the mainland, not while they are here.)
All visitors arrive at the busy ferry port in south-facing Tonsai Bay. The beach is quite attractive but the constant coming and going of boats makes it unadvisable for swimming. Most people just walk the 300m (984 ft.) across the barbell handle to north-facing Loh Dalam Bay, a spectacular, horseshoe-shaped crescent of blinding-white sand. Small beachfront outfits rent snorkel gear and conduct longtail boat tours to quiet coves with great views of coral reefs and sea life for as little as 1,000B for an all-day trip (packing your own lunch). You can rent kayaks and do a little exploring on your own, or hike to one of the island viewpoints and soak up the memorable view of back-to-back bays and rugged limestone cliffs.
Phi Phi Ley is famed for its coveted swallow nests and the courageous pole-climbing daredevils who collect them (the saliva-coated nests fetch a hefty price as the main ingredient in a much-favored Chinese soup). This smaller island is protected as a park, but can be visited as part of most day trips.
Before the 2004 tsunami, many of the settlements and hotels on Ko Phi Phi had been built illegally by squatters on land belonging to the once-pristine National Marine Park. These facilities were -- almost literally -- wiped off the map by the tragic disaster. With the help of many international volunteers who cleared the land of refuse, the crowds have returned to the island, but unfortunately so has the unplanned chaos of pre-tsunami days. Beaches are once again crammed with hotels, low-end guesthouses, and backpackers.
In the aftermath of the tsunami, the government had hinted at earmarking Phi Phi Don as a luxury destination (indeed Phi Phi already supported a number of high-end resorts on more remote beaches), but amid the unregulated rush to make as much money as possible from this once-sublime location, the plan failed. In terms of wholesale environmental degradation, we are, sadly, right back to square one.