The lagoon is actually a collapsed cave system known as a karst window.
The water depth varies significantly with the tide, sometimes becoming dry enough to walk across the sandbar.
The lagoon is completely encircled by sheer limestone walls, making it invisible from the open sea.
The emerald hue of the water is caused by limestone sediment suspended in the calm, protected environment.
Princess Lagoon, also known as the inner lagoon of Koh Hong, is a hidden emerald-water pool accessible only through a narrow limestone canyon entrance. It is situated on the interior side of the karst formations of Hong Island in Krabi province. The lagoon is characterized by its shallow, calm, turquoise water framed by towering vertical limestone cliffs. The area is part of the Than Bok Khorani National Park protected zone. Access depends strictly on tidal movements, as the entrance passage becomes too shallow or blocked during low tide. The surrounding cliffs prevent direct sunlight for much of the day, creating a distinct microclimate and unique rock formations.
From the narrow entrance channel looking inward toward the calm emerald pool against the backdrop of the cliffs.
Wear water shoes with good grip to protect your feet from sharp limestone rocks near the entrance.
Check the local tide charts carefully before departing, as the passage is impassable during low tide.
Bring a waterproof bag for your camera and phone, as you may need to wade through knee-deep water.
Attempting to enter at low tide, which can result in getting stuck on sharp rocks or needing to walk long distances across muddy sandbars.
Access is periodically restricted by the Thai National Park authorities during monsoon season or for environmental preservation.
Maintain silence to respect the natural soundscape, do not climb the fragile limestone walls, and remove all trash.
