The physics of partially submerged palaces

The Jal Mahal palace in Jaipur is a five-story skyscraper that functions perfectly while four of its floors are held underwater. You aren't looking at a floating pavilion; you are looking at the roof of a building that has been drowning for 200 years.

The palace does not sink or rot because it uses a specific gravity-based masonry technique common in 18th-century Rajput architecture. The walls are not just thick; they are tapered at the base to be several meters wide, creating a massive stone hull that handles the immense inward pressure of the surrounding Man Sagar Lake.

Engineers kept the interior dry by using a specialized lime mortar known as *araish*. This mixture was polished with marble dust until it became as smooth as glass and entirely non-porous. It turns the entire submerged structure into a single, seamless stone block that repels water molecules through sheer density.

Because the bottom four floors are encased in water, the palace stays naturally refrigerated. Even when the Rajasthan sun hits 110 degrees Fahrenheit, the submerged rooms remain at a constant, cool temperature. The water acts as a thermal heat sink, pulling the warmth out of the stones and dumping it into the lake.

The weight of the building is its own anchor. Rather than fighting the water, the palace uses the weight of its flooded lower floors to press down into the silt, preventing the buoyant force of the lake from shifting the foundation. It is a masterclass in static equilibrium where the lake is not a threat, but a structural support.

Curiously, the trees you see growing on the roof of the palace are not just for decoration. Their roots are actually planted in a layer of soil that helps distribute the weight of the upper pavilion, though the wood itself must be constantly maintained to prevent the roots from cracking the very mortar that keeps the lake out.