Phra Nang Nai Cave, widely recognized as "Diamond Cave," stands as one of the most magnificent natural masterpieces on the Railay Peninsula. Located at the northern end of East Railay and managed under the jurisdiction of Hat Noppharat Thara-Mu Ko Phi Phi National Park, this cave is a large limestone structure spanning approximately 130 meters in depth. Its geological formation showcases a complex interior of high-ceilinged chambers and intricate corridors, illustrating millions of years of geological evolution through the gradual accumulation of calcium carbonate solutions.

The primary allure that earns this cavern its diamond moniker is the presence of pristine stalactites and stalagmites that exhibit a brilliant, sparkling effect. When illuminated by the installed walkway lights, the rock surfaces glisten like scattered diamonds—a phenomenon caused by calcite crystals embedded within the limestone. For the convenience and safety of visitors, the park has installed a well-structured wooden boardwalk and a comprehensive lighting system. A major highlight is the giant stone curtain, a massive limestone formation that cascades from the ceiling like a frozen waterfall, alongside various other formations that resemble mystical figures or objects.

Beyond its aesthetic appeal, Phra Nang Nai Cave serves as a vital ecological sanctuary for several species of bats and small cave-dwelling organisms. The interior maintains a consistently cool and refreshing microclimate year-round, making it a favored retreat for tourists trekking between East Railay and Phra Nang Beach. Strict conservation measures are in place to protect the living formations, which are still actively growing through the mineral-rich water drippings. This ensures that the cave remains one of Krabi’s most precious and educational geological sites, offering a rare glimpse into the slow and silent artistry of nature.

• Since Railay is inaccessible by road, take a longtail boat from Ao Nang or Ao Nam Mao Pier to East Railay. From the East Railay pier, follow the signs and walk north through the paved path and mangrove boardwalk for about 10-15 minutes.

• Bring mosquito repellent or spray as the walking path is surrounded by dense vegetation.

• Wear comfortable walking shoes or sneakers to ensure safety on potentially slippery wooden walkways.

• Prepare a camera with low-light capabilities to capture the details of the glittering formations.

• Strictly avoid touching the stalactites and stalagmites to prevent oils from halting their growth.

• Keep your national park entrance ticket safe as it is valid for Maya Bay or Noppharat Thara on the same day.

Admission Fees:

• Thai Nationals: Adult 40 THB, Child 20 THB

• Foreign Nationals: Adult 200 THB, Child 100 THB

Opening Hours:

• Daily from 8:00 AM – 5:00 PM.