Vixen 03 (Dirk Pitt #5) by Clive Cussler

1954. Vixen 03 is down. The plane, bound for the Pacific carrying thirty-six Doomsday bombs — canisters armed with quick-death germs of unbelievable potency — vanishes. Vixen has in fact crashed into an ice-covered lake in Colorado.

1988. Dirk Pitt, who heroically raised the Titanic, discovers the wreckage of Vixen 03. But two deadly canisters are missing.