A nuclear-powered submarine belonging to the US Navy chose the wrong moment to stick its head up yesterday: The USS Montpelier was apparently ascending to periscope depth in waters off the coast of Jacksonville, reports the Navy Times, when it collided with the USS San Jacinto, an Aegis class Navy cruiser. Both ships continued to operate under their own power and the Montpelier's nuclear power plant emerged unscathed, though the San Jacinto's sonar dome suffered damage. No injuries were reported. Both the San Jacinto and Montpelier were conducting routine training, and the Navy is investigating. (More Navy stories.)