However, it may have not been the first. According to the New York Times a recent archaeological find could show very early Europeans traveled the seas well before their Australian Aborigine brethren. Tools found on the island of Crete seem to be at least 130,000 years old and maybe up to 700,000 years old. The tools are probably closer to 130,000 years old than the latter but this still pushes seafaring back 70,000 years!
The fascinating thing about this large time period is that it was one where Europe was populated by more than one type of human. Our Homo Sapien forefathers lived alongside and competed against Homo Heidelbergensis and Neanderthals. The fact that the tools look like non-Homo Sapien gives some credence to a proto-human origin (though just because tools like like another tool culture does not automatically mean they are related).
I can only imagine the drive and reason behind the early European seafarers. In the time before trade there would be no material need for sea travel. With very small populations nomadic peoples should have no understandable reason of sailing the Mediterranean. Some spirit of adventure, maybe, inspired a person or small clan to build a raft and travel where the currents and winds took them.