[[caption-width-right:350: Most of the primary cast (Ed, Gail, Murphy, Paul and Hal)]]

->''"This is the year two thousand and twenty. The place is the Challenger seamount, the top of an underwater mountain, a complex beneath the sea. 250 men, women and children live here, each of them a scientist-pioneer. For this is our last frontier, a hostile environment which may hold the key to tomorrow. Each day these oceanauts meet new challenges, as they build their city beneath the sea. This is Sealab 2020."''
-->-- '''OpeningNarration'''

A short lived Creator/HannaBarbera cartoon, airing in 1972. The show followed the exploits of the crew of Sealab, an underwater research station devoted to studying, exploring, and protecting underwater marine life. The show had a short run, with only 13 episodes aired (and three left unfinished).

The show wasn't well remembered except for occasional early morning repeats on Creator/CartoonNetwork, before the burgeoning program block Creator/AdultSwim [[GagDub parodied]] it as ''{{WesternAnimation/Sealab 2021}}''.
!!Tropes featured in this show:

* AllAnimalsAreDogs: As Hal said, "basking sharks are like the puppies of the ocean."
* ColorCodedCharacters: As listed below the wet suit the characters wear are color coded by position.
* DistressedDamsel / DistressedDude: Bobby and Salli need to be rescued in the pilot
* DrivenToMadness: Due to green fever, a minor character tries to sabotage Sealab
* FamilyUnfriendlyViolence: One episode deals with a hunter tracking and trying to kill a whale.
* GreenAesop: More often than not.
* HeelFaceTurn: Several examples to put over the GreenAesop.
* HollywoodScience: Mostly averted, in a lot of the plots stay fairly accurate.
* ItWasHereISwear: Nobody at first believes Gail when she sees the giant squid.
* KnowWhenToFoldEm: In "Collision of the Aquarius", while the Sealab crew plan to cut their way into the eponymous submarine's nuclear reactor room from the bottom, the sub's captain, Glenn, tries to break into the reactor himself through the hatch, doubting that Sealab would make it in time. Captain Murphy knows that this is dangerous, since there is a possibility that the reactor's automatic carbon control system won't work, resulting in Glenn attempting to insert the carbon rods by hand without shielding, meaning he would risk radiation poisoning. Glenn only gives up on his folly when he sees Sealab successfully able to get into the reactor room first.
* LimitedAnimation: Like most cartoons of its era.
* LimitedWardrobe: Since the show takes place in an undersea base, it's sort of a JustifiedTrope. Every one wears a diving suit (orange for scientist, blue for other job, yellow for student)
** Slightly subverted when each characters get a helmet when they go diving.
* NoNameGiven: A good chunk of the other workers in Sealab.
* RisingWaterRisingTension: In "Green Fever", a red alert is signaled after a supply ship's concrete mooring, cast off during a hurricane, unwittingly strikes Sealab's control dome and splits a major section of the shell, causing it to start flooding.
* UnderwaterBase[=/=]UnderwaterCity: Sealab, of course.
* WhatHappenedToTheMouse: There are clearly lots of workers in Sealab but outside of the primary cast most only get shown in one episode to never be mentioned again.