MST3K Ep. K01 - "Invaders from the Deep"
This is the first episode of Mystery Science Theater 3000 ever aired.
No fan copy is known to exist.
Movie version of Gerry & Sylvia Anderson's Supermarionation puppet series Stingray, about the eponymous super-submarine operated by the World Aquanaut Security Patrol (WASPs), fighting aquatic creatures who attempt to take over the planet.