Fit for a Bond villain lair, this hidden pool consists of a platform that is lowered to any depth from 1-inch to 6-feet. The water is kept in reserve and is pumped into the pool bed. When the platform is raised up, it forms a decorative patio perfect for a picnic table or lounge chairs. However, at the push of a button, the platform can be lowered in 2-minutes. Continue reading for more clever designs that actually exist.