AN 'EMPIRE' AT 40: THE CREATURE FROM THE PARKWAY LAGOON!

As Artoo's periscope guides him to shore of the new world they have crashed in, the Astro Droid is unaware until too late that a Dragonsnake creature is getting ready to eat him! 

With the previously filmed footage of the Dragonsnake's residing under the waters of Dagobah not having proved successfully realized at Elstree several months back, George Lucas and Richard Edlund undertake the subsequent re-shoot alongside ILM, literally turning their boss's Parkway House swimming pool into the swampy environs.

The scene with Artoo underwater with a periscope was first devised for the original Star Wars, with the droid planned to be in the Dia Noga scene within the Death Star garbage chute, envisaged in the script's early Fourth Draft. 

BEHIND THE SCENES IMAGE: HERE BE DRAGONS!

On the grimy swamp set of Dagobah at London's Elstree Studios in the summer of 1979, near Luke Skywalker's buried X-wing fighter, a wet-suit clad technician (Digby Milner - SFX asst) tends to the prop of the underwater based Dragonsnake creature that promptly devours Artoo Detoo. The original UK filmed effect shot of the beast's first appearance, which looks like it had big scales, was ultimately deemed unusable and a replacement shot was filmed in the US months later-within George Lucas's house pool no less!

Originally, an entirely different kind of underwater beast had been envisaged to attack Luke whilst he and Artoo were both swimming from their fighter to the shore, in this great Ralph McQuarrie concept...