Air date: 1977-09-22

Runtime: 49 min

Schubert threatens to cause worldwide flooding by using powerful microwaves to melt Earth's polar ice caps, unless the government turns Mark Harris over to him.

Air date: 1977-10-13

Runtime: 49 min

When a multimillion-dollar underwater probe malfunctions and begins attacking any ship that travels near it, Mark must reason with its highly advanced brain and convince it to stop.

Air date: 1977-10-18

Runtime: 48 min

Mark, investigating a power outage, discovers a centuries-old hawk statue from the legendary civilization of Mu. The statue, when used properly, can remove the power from a large area. Schubert discovers the power of the hawk statue and Mark must prevent him from taking it.

Air date: 1977-10-25

Runtime: 48 min

The oceans are leaking through a fissure in the ocean floor. A con-man named Muldoon agrees to guide Mark through the fissure to investigate. However, Mark is unaware either that giants inhabit the other side of the fissure or that Muldoon has already stolen gold from one of them.

Air date: 1977-11-01

Runtime: 48 min

Schubert threatens to cause worldwide flooding by using powerful microwaves to melt the earth's polar ice caps, unless the government turns Mark Harris over to him.

Air date: 1977-11-08

Runtime: 48 min

When a multimillion-dollar underwater probe malfunctions and begins attacking any ship that travels near it, Mark must reason with its highly advanced brain and convince it to stop

Air date: 1977-11-22

Runtime: 48 min

Mark, investigating a power outage, discovers a centuries-old hawk statue from the legendary civilization of Mu. The statue, when used properly, can remove the power from a large area. Schubert discovers the power of the hawk statue and Mark must prevent him from taking it.

Air date: 1977-12-06

Runtime: 48 min

The oceans are leaking through a fissure in the ocean floor. A conman named Muldoon agrees to guide Mark through the fissure to investigate. However, Mark is unaware that giants inhabit the other side of the fissure and Muldoon has already stolen gold from one of them.

Air date: 1977-12-13

Runtime: 48 min

Using his genetic scientists, Schubert produces a giant jellyfish which he intends to release unless his extortion demands are met.

Air date: 1978-04-18

Runtime: 48 min

Mark is somehow linked with a man named Billy, existing in a wild west town, who appears to be his twin. Investigating, Mark arrives in the town and discovers Billy had the same webbing as Mark but has had it removed.

Air date: 1978-04-25

Runtime: 48 min

Schubert attempts to make a satellite weapon to knock out the Earth's communications. However, to power the weapon he needs the energy crystals protected by a forcefield under the ocean. The crystals actually power the forcefield that protects an underwater city.

Air date: 1978-05-02

Runtime: 90 min

An underwater landslide transports Mark to Verona, Italy... in the days of Romeo and Juliet.

Air date: 1978-06-06

Runtime: 90 min

C.W. develops a Jekyll-and-Hyde personality after swallowing a mysterious liquid.