Seafaring before the Neolithic -- circa 7th millennium BCE -- is a controversial issue in the Mediterranean. However, evidence from different parts of the Aegean is gradually changing this, revealing the importance of early coastal and island environments. The site of Ouriakos on the island of Lemnos (Greece) tentatively dates to the end of the Pleistocene and possibly the beginning of the Holocene, circa 12,000 BP... Obsidian, or 'volcanic glass', has been a preferred material for stone tools wherever it is found or traded. It also absorbs water vapour when exposed to air -- for instance, when it is shaped...