Located in Biscayne Bay, just north of Sands Key.

Juan de Liguera chart (1742) shows Mascaras (SP. - masks) Alaña chart (1743) also shows Mascaras. 1733 Plate Fleet wreck chart shows Mucasas. William Roberts, in his First Discovery and Natural History of Florida (1763) uses Mucaras. DeBrahm (1772) named each of these keys separately, North to South as follows: Los Paradizos, Soldiers, Knox, and Pollock. The 1861 Bache Coast Survey so names these keys.

Bernard Romans, who visited these keys in 1774, wrote that these were "Seven rocks called Mascaras," which he said had been ''Ill copied on English charts as Mucares."