The Franchthi or Frankithi cave is a prehistoric site in the Greek Peloponnese. The cave shows occupation from the epipalaeolithic c, 10,000 BC and, following a hiatus, it was reoccupied in the Mesolithic between 7500 and 6000 BC.
Obsidian items from the cave have been traced to the island of Melos 80 miles away by sea, which indicates that boats were used in the period. Around 5800 BC evidence of domesticated animals appears in the archaeological record at the cave.
The Francthi Cave, on the coast of south east Greece, is a remarkable site which, according to the archaeologists who excavated there has a 33 feet deep unbroken series of deposits covering the period from 20,000 BC down to 3,000 BC - in other words, from the far prehistoric
It is likewise inconceivable that the obsidian could have reached the Francthi Cave by accident.
The only remaining conclusion is that these primitive Stone Age savages were sufficiently accomplished sailors that they were able to explore the Mediterranean almost out of sight of land and return home with desirable objects such as pieces of obsidian.