A dirigible (or airship) was a powered balloon aircraft which was kept buoyant by a lighter than air body of gas. These were used on Earth up to and during the 20th century.
As a child, Jean-Luc Picard built model airships. (TNG: "Booby Trap")
In the holosuite program Julian Bashir, Secret Agent, set in the 1960s, Doctor Bashir fell out of a dirigible over Iceland, which made the character Anastasia Komananov believe he was dead. However, he had a parachute with him and found a submarine waiting for him when he landed. (DS9: "Our Man Bashir")