On the way down I saw nothing. The On grooves and splinters of submerged water was a blur of teal fringed planks. This was the slave ship Camargo, with rusty shadows, darkening, about twenty feet below, to a sickly emerald. I followed a rope strung between a buoy and a stake in the seabed, pausing occasionally to pinch my nose and adjust my sinuses to the pressure. Just beyond the thermocline, where the temperature abruptly drops, a hand emerged from the murk and grabbed me by the wrist, dragging me the last few inches to the bottom. The silt was as soft as tapioca pudding. It swallowed my hand, then my arm and shoulder; the deeper I pushed, the more I suspected that it might go on forever. Finally, I touched wood, feeling a chill colder than the water's as I ran my fingertips over the which carried five hundred souls across the Atlantic before it burned.

It was the sixth of November, and I was diving with a group of maritime archeologists in Angra dos Reis. A verdant bay three hours from Rio de Janeiro, it's a kind of Brazilian Hamptons, where yachts fill the marinas and Vogue once sponsored a party for New Year's Eve. But in the nineteenth century it was mostly plantations-sugarcane near the water and coffee just beyond the jagged mountains that ring the area like snaggleteeth. They thrust up around me as I resurfaced, pressing a button to inflate my scuba kit's buoyancy-control device. The researcher who'd guided me to the wreck showed me the soot under our fingernails. Then we swam back to the dive boat, a creaky, flat-bottomed rental whose Portuguese name meant "With Jesus I Will Win."