Transparent Ice. The water of Lake Baikal is renowned for being some of the clearest in the world. When the lake freezes during the winter, an amazing phenomena takes place: large shards of transparent ice form on the surface of the lake, giving the amazing appearance of turquoise ice.
An icicle is a spike of ice formed when water dripping or falling from an object freezes.
A grotto is a natural or artificial cave used by humans in both modern times and antiquity, and historically or prehistorically. Naturally occurring grottoes are often small caves near water that are usually flooded or liable to flood at high tide.