DAKAR, Senegal - Staring out to sea on a flawlessly sunny day, underwater archaeologist Ibrahima Thiaw visualizes three shipwrecks once packed with slaves that now lie somewhere beneath Senegal's Atlantic waves.

He wants more than anything to find them.

Thiaw has spent years scouring the seabed off the island of Goree, once a West African slaving post, never losing hope of locating the elusive vessels with a small group of graduate students from Dakar's Cheikh Anta Diop University.