I once believed that too. But, if it was Santorini, we'd know a whole lot more about it. I'm leaning toward the 9-12,000 years ago time frame.
Dr Robert Schoch thinks it may have been on the Sunda Shelf around Indonesia. As explained in his book, Voyages Of The Pyramid Builders.
Quite a trip from Egypt. Herodotus recounted the story of a Phoenician trip around Africa but he didn't mention anything like a voyage to Indonesia.