A blue iceberg is visible after the ice from above the water melts, causing the smooth portion of ice from below the water to overturn. The rare blue ice is formed from the compression of pure snow, which then develops into glacial ice.
Icebergs may also appear blue due to light refraction and age. Older icebergs reveal vivid hues of green and blue, resulting from a high concentration of color, microorganisms, and compacted ice.
According to dailymail: While on an expedition to Antarctica, Alex Cornell was stunned when he spotted an ‘alien’ blue iceberg floating across the landscape.
Unlike the icebergs around it, the surreal sleeping beast was completely free of snow and debris, revealing a polished azure surface.
What Mr Cornell witnessed in Drake Passage was an incredibly rare phenomenon; a flipped iceberg caused by an imbalance in frozen water.