Both were created by Irwin Allen, which enabled the film's sets, costumes, props, special effects models, and sometimes footage, to be used in the production of the television series.

[1] Voyage to the Bottom of the Sea was the first of Irwin Allen's four science fiction television series (the three others being Lost in Space, The Time Tunnel, and Land of the Giants), and the longest-running.

The Seaview is officially for undersea marine research and visits many exotic locations in the Seven Seas, but its secret mission is to defend the planet from all world and extraterrestrial threats[2] in the then-future of the 1970s.

The season introduced a diving bell and a mini-submarine, and the first episodes featuring extraterrestrials (Don Brinkley's "The Sky is Falling") and sea monsters.

It was also established that while essentially a marine research vessel, SSRN Seaview was also part of the U.S. nuclear armed fleet (most notably defined in William Read Woodfield's episode, "Doomsday").

The most important change in the series occurred during this season when a notably redesigned Seaview interior was introduced, along with the Flying Sub, a yellow, two-man mini-submarine with passenger capacity.

The Seaview control room was expanded and a large rectangular panel screen of flickering lights was added.

The ship's enlisted men were also given more colorful uniforms (red or light blue jumpsuits) and white Keds Champion sneakers.

He filmed the scenes in the Flying Sub for "The Monster's Web" before hospitalization, requiring a stand in and other characters taking over his lines.

These episodes didn't feature his character at all, while in one story "The Menfish" Gary Merrill guested as Admiral Park, a colleague of Nelson's who substituted for him.

In one episode, the Seaview's officers and crew encountered Nazis who believed World War II was still ongoing.

One of those three stories was about a hostile foreign government trying to steal a strange new mineral with the aid of a brainwashed Admiral Nelson.

The fourth and final season of Voyage began with Victor Jory playing a five-centuries old alchemist and the Seaview is threatened by the hydrodynamic effects of a major volcanic eruption.

Starting with the eighth episode of the season, there were revamped opening credits depicting action sequences and the stars' pictures in color set on a sonar board design.

The final scene of the show had Nelson and Crane sitting in the seldom-used easy chairs on the port side of the observation nose discussing how fast time goes by.

A new darker, more serious theme composed by Jerry Goldsmith was introduced at the beginning of the second-season episode "Jonah and the Whale", but this was quickly replaced by the original version.

In Region 2, Revelation Films has released the entire series on DVD in the UK in four complete season sets.