"The woman... told officials she was swimming in a canal when she noticed a door and entered it. She said she eventually became lost..."

"... and ended up three miles away from where she first began, surviving on a can of ginger ale she discovered unopened along the way. Police are trying to determine if the woman was actually underground for three weeks. They say the health officials they have consulted believe it is more likely the woman was only in the sewer for two or three days. 'We don’t feel that there was any crime committed,' Ted White, a police spokesperson, said. 'But the biggest question is, is her story credible? Was she actually down there the whole time?'"

From "Naked woman rescued from Florida sewer after driver hears her screaming/Delray Beach fire rescue says woman sustained superficial injuries and had been reported missing three weeks earlier" (The Guardian).