Smirnov resided in Framingham, Massachusetts in 2003 and was employed as a systems programmer at Fidelity Investments in Marlborough, Massachuetts. She was on a vacation in Florida at the time of her disappearance. She was last seen at approximately 5:00 p.m. on November 9, 2003, as she was scuba diving from a boat in the Cocker Reef area off the southwestern tip of Key Largo, just southeast of Islamadora, Florida. She had gone to the Cocker Reef with a dozen other divers aboard the Tropic Vista boat.

Smirnov's diving partner says they were swimming in approximately forty feet of water when they realized they should return to the boat. They were on their way back when Smirnov's partner got a little ahead of her. When he turned back to find her, she had disappeared. Her partner was too far away from the boat to get back on his own and was later rescued in good condition by the Coast Guard.

A lobster fisherman found Smirnov's compensator, regulator, scuba tanks and dive computer off of Islamadora thirteen days after her disappearance and turned them into police. The equipment was identified by Smirnov's husband. There has been no sign of Smirnov, however. She is presumed lost at sea, but her body has not been recovered.