The Princess Sunantha Memorial, or the Pyramid of the Drowned Queen, is a stupa dedicated to Her Majesty Queen Sunanta Kumari Ratana, located within Khao Phliu National Park in Chanthaburi Province. It was constructed during the reign of King Rama V in 1881 to commemorate the queen, who had visited the beautiful Phliu Waterfall in 1874 and was enchanted by its natural beauty. This memorial, shaped like a pyramid, was specifically designed based on the king's understanding that "creating a monument in a different form might not endure, as it sits in the wilderness without guardians. Thus, just as the pyramids of Egypt stand the test of time, this small pyramid should also remain steadfast amid the forest and the soft sounds of the flowing stream." The Princess Sunantha Memorial is not only a tribute to the queen but also a symbol of resilience against the passage of time, harmoniously nestled in its serene natural surroundings.