The second American submarine to be involved in a major accident.
On January 15, 1916, the E-2 was undergoing an overhaul at the New York Navy Yard. An errant spark ignited hydrogen gas, causing a large explosion and fire. Four of the sub's crew of 22 were killed in the fire, and another seven were injured. Although the vessel was placed out of commission for two years after the blast, the E-2 was recomissioned and saw minimal action in the First World War.
(Not to be confused with E2!)