Completed in Finland in 1987, the Mir submersibles are each 7.8 meters (25.6 feet) long and weigh 18.6 tons. They are garaged under two steel tent-like structures aft on the starboard side of their mother ship Keldysh. Here, Mir 1 is being lowered into the sea for a dive. Two observers and a pilot can be accommodated inside each sub’s 6.9-foot-diameter nickel-steel pressure sphere. They have a maximum diving depth of 6000 meters (20,000 feet). The Mirs have made over 50 dives to the Titanic site since 1991. (P. P. Shirshov Institute of Oceanology)