S4E1 - Point of No Return
Mike is trapped in a ""scubasphere"" when the cable attached to it snaps.
Jan. 7, 1961, midnight
S4E2 - River Treasure
While surveying a remote river in the South American jungle, Mike is threatened by the jealousy of a man prospecting for emeralds with his wife.
Jan. 14, 1961, midnight
S4E3 - The Destroyers
Mike investigates the source of a radar jamming signal that caused two ships to collide.
Jan. 21, 1961, midnight
S4E4 - Vital Error
A famous newsman, convinced that he has a fatal illness, tries to end his life in such a way that his wife can collect his insurance, with Mike as a witness.
Jan. 28, 1961, midnight
S4E5 - The Dancer
A scuba diving ballerina faces the possibility of underwater amputation when she catches her foot between the buckled plates of a sunken freighter.
Feb. 4, 1961, midnight
S4E6 - Sperling of Lamatsue
After being accidentally caught in a fishing net, Mike challenges an Asiatic warlord by trying to retrieve a cache of medical supplies that the dictator has dumped into a river.
Feb. 11, 1961, midnight
S4E7 - Rescue
Unaware that two of his treasure-hunting friends are trapped inside, Mike sets charges to blow up a sunken ship that is a menace to a busy shipping lane.
Feb. 18, 1961, midnight
S4E8 - Mercy Trip
Mike scouts a path through mine-infested waters so that medical supplies can reach a China Sea port hit by a cholera epidemic.
Feb. 25, 1961, midnight
S4E9 - Hot Tracer
Mike's efforts to retrieve a pair of radioactive cylinders are complicated by the presence of a headstrong youth to whom he's been giving diving lessons.
March 4, 1961, midnight
S4E10 - Sonar Story
Mike uses sonar to foil a gang of underwater heroin smugglers.
March 11, 1961, midnight
S4E11 - Amigo
A young Mexican boy helps Mike locate a safe entrance to an underwater fossil cave.
March 18, 1961, midnight
S4E12 - The Aquanettes
Mike faces sharks and other unexpected difficulties while working with three pretty women undergoing astronaut training.
March 25, 1961, midnight
S4E13 - Survival Kit
Mike is hired by a local German consul to salvage a survival kit from the wreckage of a Nazi warplane in the Caribbean.
April 1, 1961, midnight
S4E14 - Expedition
While helping his former history professor search for pirate treasure off the North Carolina coast, Mike finds evidence that the underwater cave said to house the treasure has been tampered with.
April 8, 1961, midnight
S4E15 - Bionics
Mike convinces a reluctant daughter to continue her father's work after he is killed testing an underwater electrical detection device.
April 15, 1961, midnight
S4E16 - The Defector
A man bribes Mike to continue giving lessons to an inept diving student whom he's stopped teaching.
April 22, 1961, midnight
S4E17 - Niko
Mike heads a three-man team in an effort to disarm a pair of unexploded torpedoes at the bototm of a West Coast harbor.
April 29, 1961, midnight
S4E18 - Cougar
A restless youth and a college girl complicate Mike's attempts at capturing a poisonous lionfish.
May 6, 1961, midnight
S4E19 - Sub Hatch
A heroic test pilot from the Korean War has his mettle tested when he must spend 24 hours with Mike in a makeshift decompression chamber after a dive to prevent the bends from killing him.
May 13, 1961, midnight
S4E20 - The Octopus Story
Markings on the body of a dead diver convince a marine biologist that a tropical lagoon is inhabited by a killer octopus.
May 20, 1961, midnight
S4E21 - Quicksand
One salvage diver disappears while diving on a sunken yacht off the coast of Yucatan, and Mike tries to see that two others don't share his fate.
May 27, 1961, midnight
S4E22 - Lost Island
Mike teams up with a Mexican prison escapee to uncover nefarious activity on an uncharted Pacific atoll off the coast of South America.
June 3, 1961, midnight
S4E23 - Baby
Mike must get past Jivaro Indians who are blocking his passage downriver as he attempts to get a young missionary's baby to a hospital for medical attention.
June 10, 1961, midnight
S4E24 - Confidential Mission
Mike poses as a tourist on vacation as he tries to locate a hidden underwater missile launcher in the Caribbean.
June 17, 1961, midnight
S4E25 - Underwater Pirates
Pirates try to snatch a sunken freighter away from Mike before he can salvage it for an old Navy buddy.
June 24, 1961, midnight
S4E26 - The Meet
While working for the U.S. Treasury to break a counterfeiting ring, Mike intercedes in a kidnapping.
July 1, 1961, midnight
S4E27 - Dark Evil
A pretty woman and her father, vacationing in the Bahamas, become killers after inadvertently eating a variety of fish that causes hallucinations.
July 8, 1961, midnight
S4E28 - Sunken Car
A sunken truck points Mike to the murder of a political boss, and the killer is the father of a good friend of Mike's.
July 15, 1961, midnight
S4E29 - Hit and Run
Mike goes after an egocentric movie star who injured a friend of Mike's in a hit-and-fun speedboat accident.
July 22, 1961, midnight
S4E30 - The Saint Story
While searching a Latin American harbor for a sunken statue, Mike discovers a UHF homing beacon being used to guide submarines into the port.
July 29, 1961, midnight
S4E31 - Impostor
A dead ringer for Mike is stealing diamonds from a sunken sports cruiser, but when Mike is accused of the crime, he is unable to establish an alibi due to his current top-secret mission.
Aug. 5, 1961, midnight
S4E32 - Superman
While on a diving expedition in Guatemala, a woman seeking to slow down her husband's frantic lifestyle deliberately sinks the boat they share, unaware that her husband is a diabetic and his insulin supply will be lost with the vessel.
Aug. 12, 1961, midnight
S4E33 - Roustabout
Mike's assistant is trapped underwater by an overturned truck containing drums of poison that could endanger a South American city's water supply.
Aug. 19, 1961, midnight
S4E34 - P.T. Boat
Mike helps test a remote control guidance device invented by a rich eccentric.
Aug. 26, 1961, midnight
S4E35 - Starting Signal
A naval officer of a Caribbean nation is sabotaging a series of experiments Mike is conducting with the Coast Guard.
Sept. 2, 1961, midnight
S4E36 - Skipper
During hydroplane races, a friend of Mike's rams his craft into a Coast Guard ship, leaving Mike to investigate.
Sept. 9, 1961, midnight
S4E37 - Crime at Sea
Mike helps the daughter of his old UDT Commander investigate the man's death, which she believes was murder.
Sept. 16, 1961, midnight
S4E38 - Round Up
Mike must find and disarm a torpedo that's been sent into the outflow tube of a hydro-electric plant.
Sept. 23, 1961, midnight