We've heard of rainbows in the sky, but coming out of the ground? Not so common.
A stunning pool that has developed extraordinary rainbow-coloured water has become a hit with tourists.
The unique spring formed its unusual band of colours due to chemical reactions caused by tourists throwing coins into its hot water.
Over the years the coins and other debris blocked the pool's heat vents, reducing the water's temperature and causing different types of bacteria to grow.
The bacteria worked their way at the water's edge, creating a red and yellow ring around the pure blue centre.
IT consultant Arun Yenumula took the photograph of the pool, called Morning Glory, while on holiday with his wife at Yellowstone National Park, in Wyoming, America.
The 30-year-old said: 'I had heard about the pool from friends and when I saw it I thought it was simply unbelievable. Each colour represents a different type of heat-seeking algae.'
Strange but true!