Even though sound waves in water and sound waves in air are basically similar, the way that sound levels in water and sound levels in air are reported is very different, and comparing sound levels in water and air must be done carefully.
Melanocytes are found in the stratum basale layer. About 1 in every 5 to 10 cells in this layer is a melanocyte. Melanocyte number is the same in all races. In different races, the number of melanocytes is THE SAME. In light skinned people, the melanin is concentrated deep in the epidermis, particularly in the stratum basale layer. Differences in skin colour depend on how much melanin is produced, the size of the melanosomes, and the degree to which they agregate.
As a fast spreading cancer, this can quickly move into the surrounding skin and organs. Described as a cancer of the melanocytes (the cells which produce melanin: a pigment responsible for color in the skin), melanoma can actually start in many areas of the body. However, it is predominantly found in the skin.