Season 4

118 :04x01 - Point of No Return

This time it's Mike who needs rescuing when the cable attached to his Scubasphere breaks.
Guest Stars: Joyce Meadows as Dorothy Maybrook | Paul Birch as Dr. Bainbridge | Franco Corsaro as Prof. Antone Ricardees | Ross Elliott as USCG Lt. Dave Tulley | Tom West as TBD | Ronald Brown as Vic Jennings
Director: Leon Benson

119 :04x02 - River Treasure

Mike happens upon a jealous couple prospecting for emeralds while surveying a remote river in South America.
Guest Stars: Linda Lawson as Jill Marzack | Anthony Caruso as Tom Marzack
Director: Leon Benson
Writer: Don Archer

120 :04x03 - The Destroyers

Mike investigates when a radar jamming signal causes two sea vessels to collide with one another.
Guest Stars: Ross Elliott as USCG Lt. Dave Tulley | Paul Maxwell as Dr. Neal Martin | Harlan Warde as USCG Cmdr. Ben White | Karl Held as USCG Radarman
Director: Leon Benson

121 :04x04 - Vital Error

A newspaperman becomes convinced that he's dying from a fatal illness and tries to end his life in such a way that his wife can collect his insurance.
Guest Stars: Reed Hadley as Fred Darrow | Aline Towne as Elaine Darrow | William Woodson as Dr. John Gregory | Ross Elliott as USCG Lt. Dave Tulley | Nancy Reynolds as Nurse Davis | Jack Warford as USCG Radioman (as John Warford)
Director: Leon Benson

122 :04x05 - The Dancer

Mike must rescue a scuba diving ballerina when she catches her foot between loose plates of a sunken freighter.
Guest Stars: John Hackett as Bob Forrester | William C. Flaherty as USCG Cmdr. Frank Martin, MD (as Bill Flaherty) | Dona Lorenson as Anna Buonanova (as Dana Lorenson)
Director: Leon Benson

123 :04x06 - Sperling of Lamatsue

Mike must retrieve a cache of medical supplies that were dumped in a river before a local witch doctor can get his hands on them.
Guest Stars: John Barclay (2) as Dr. Jan Sperling | Sharon Bercutt as Rayna | Kimo Mahi as Vinshaw | Al Santos as TBD
Director: Leon Benson
Writer: Sylvia Drake

124 :04x07 - Rescue

Mike sets a charge to blow up a sunken ship that is a threat to a busy shipping lane but is unaware that a treasure hunting friend is trapped inside.
Guest Stars: Jack Ging as Lou James | Sue Randall as Mary Carter | Ross Elliott as Lt. Dave Tulley
Writer: Jack Rock

125 :04x08 - Mercy Trip

Mike is assigned to chart a path through mine-infested waters so that medical supplies can reach a port city suffering from an epidemic of cholera.
Guest Stars: Gregory Gaye as Mayor Sunander (as Gregory Gay) | Vitina Marcus as Tali (as Ventina Marcus) | Ken Drake as Dr. Levy
Director: Leon Benson

126 :04x09 - Hot Tracer

A youth to whom he's been giving diving lessons complicates Mike's efforts to retrieve a pair of radioactive cylinders.
Guest Stars: Robert Montgomery Jr. as Chan Harrington III | Tyler McVey as Dr. Widmer | Wayne Mallory as Hendricks | Darlene Tompkins as Ginny
Writer: Don Moore

127 :04x10 - Sonar Story

Mike goes up against underwater heroin smugglers and uses sonar to foil their scheme.
Guest Stars: Mark Dana as Dr. Briggs | Juli Reding as Blonde Woman (as Juli Reding Hunter) | Joseph Breen as Mr. Hart | Joan Patrick as Brunette Woman | Phil Dean (1) as USCG Commander Kelly | Michael Keith as Helicopter Lookout
Director: Leon Benson

128 :04x11 - Amigo

With the help of a young Mexican boy, Mike locates a safe entrance to an underwater fossil cave.
Guest Stars: Vikki Dugan as Cheryl Carter | Noel Drayton as guest star | Rafael Lopez as guest star | Eugene Martin as guest star

129 :04x12 - The Aquanettes

Mike helps three women undergoing astronaut training and faces unexpected perils.
Guest Stars: Valerie Allen as Dana Perry | Nan Adams as Barbara Clinton | Gloria Marshall as Joanna Sue Toliver | Mary Lawrence (1) as Dr. Barnes
Director: Leon Benson

130 :04x13 - Survival Kit

A German consulate hires Mike to salvage a survival kit from the wreckage of a World War II U-Boat.
Guest Stars: Gertrude Michael as Mrs. Friedrich | Bill Berger as Carl Friedrich | King Moody as Consul Baumer | Paul Dixon (1) as Carl's Diving Partner
Director: Leon Benson
Writer: Don Archer

131 :04x14 - Expedition

Mike helps his former college history professor search for buried pirate treasure off the North Carolina coast.
Guest Stars: Robert F. Simon as Professor Aaron Halliday | Lisabeth Hush as Zoƫ White | Irene Tedrow as Naomi Roundtree | Mike Steen as Sonny Kendall
Director: Leon Benson

132 :04x15 - Bionics

After a man is killed testing an underwater device, Mike convinces his hesitant daughter to continue her father's work.
Guest Stars: Kathie Browne as Kathryn Drayton | Robert Karnes as USCG Commander Flint
Writer: Jack Kelsey

133 :04x16 - The Defector

An man offers to pay Mike extra to continue teaching diving lessons to an inept student.
Guest Stars: Lili Kardell as Carole Sloan | Robert Sampson (1) as Bob Hicks | Francis Bethencourt as Vincent Morale | Ted Knight as Steve Powery | Charles Swain as Alfred
Director: Leon Benson

134 :04x17 - Niko

Mike and two other divers try to disarm a pair of unexploded torpedoes at the bottom of a busy harbor.
Guest Stars: Lane Bradford as Frank Judd | William C. Flaherty as USCG Lieutenant (as William Flaherty) | Dale Ishimoto as Niko Sugimoto
Director: Leon Benson
Writer: Don Archer

135 :04x18 - Cougar

Mike's attempts to capture a poisonous lion fish are complicated by the presence of a restless youth and his girlfriend.
Guest Stars: Robert Ridgely as Cougar Norris (as Robert Ridgley) | Susan Silo as Leilani
Director: Leon Benson

136 :04x19 - Sub Hatch

A test pilot must spend 24 hours in a decompression chamber after a dive in order to keep the bends from killing him.
Guest Stars: John Hudson (1) as Jerry Blaine | George Johnson (2) as USCG Lt. Hartwell | Bill Edwards (1) as USCG Commander Murdock
Director: Leon Benson
Writer: Don Moore

137 :04x20 - The Octopus Story

Markings on the body of a dead diver convince a marine biologist that a killer octopus inhabits a lagoon. Mike must prove or disprove the theory.
Guest Stars: Ken Curtis as Dean Austin | Jan Harrison as Betty Rainard
Director: Leon Benson

138 :04x21 - Quicksand

Mike tries to make sure two salvage divers don't disappear while diving on a sunken boat off the coast of Yucatan. It seems as though a previous diver vanished completely.
Guest Stars: Corey Allen as Young | Ric Marlow as Slade | Kathie Browne as Eleana Dales | Richard Bermudez as Pedro
Director: Leon Benson

139 :04x22 - Lost Island

Mike and an escaped Mexican convict uncover nefarious activity on an atoll off the South American coast.
Guest Stars: Roy Dean as Johnny Gerard |
Uncredited: Troy Melton as Pollywogs Leader
Director: Leon Benson
Writer: E.M. Parsons

140 :04x23 - Baby

Hostile natives interfere with Mike's passage downriver when he attempts to get a missionary's baby to a hospital for medical attention.
Guest Stars: Denise Alexander (1) as Carolyn Tucker | Beau Bridges as Warren Tucker | John Zaremba as Dr. Bruney
Director: Leon Benson

141 :04x24 - Confidential Mission

Mike goes undercover once again, this time as a tourist, in order to locate an underwater missile launcher in the Caribbean.
Guest Stars: Terry Becker as Alcott | Ken Drake as Steve Walker | Jan Arvan as Police Lieutenant | Dehl Berti as Yacht Captain
Director: Franklin Adreon
Writer: Arthur Weiss

142 :04x25 - Underwater Pirates

Mike is hired by an old Navy buddy to salvage a sunken freighter but pirates are out to make sure they get there first.
Guest Stars: Ron Hayes as Sam Carter | Stewart Bradley as TBD | Stuart Bradley as Brady | John Considine as Doak | Nan Peterson as Norma Carter | Robert Christian (2) as Charlie
Director: Franklin Adreon

143 :04x26 - The Meet

Mike gets involved in counterfeiting and kidnapping when he's hired to work for the Treasury Department.
Guest Stars: Larry Pennell as Steve | Lorrie Richards as Penny | Robert Clarke (2) as Federal Agent Bill Saunderman | Richard Evans as Chaz | Bill Catching as Whitney
Director: Eddie Davis
Writer: E.M. Parsons

144 :04x27 - Dark Evil

A woman and her father vacationing in the Bahamas become homicidal after eating a type of fish that causes hallucinations.
Guest Stars: Margie Regan as Lucille Brandon | Michael Whalen as Oliver Brandon | Peter Forster as Dr. Alan Clark | James Forrest as Police Inspector Lyons
Director: Leon Benson

145 :04x28 - Sunken Car

Mike discovers that a sunken truck is tied into the murder of a political boss and the killer is someone close to him.
Guest Stars: John Marley as Frank Johnson | Dan White (1) as Sheriff Wyatt Walsh | Ann Morrison as Mrs. Emmanuel Krag (as Anne Morrison) | Don Devlin as Ted Johnson | Warren Drew as Ed | Doug Carlson as USCG Lieutenant
Director: Franklin Adreon

146 :04x29 - Hit and Run

After a friend of his is seriously injured in a speedboat accident, Mike goes after the movie star responsible.
Guest Stars: Nancy Valentine as Virgie Bryant | Patrick Waltz as Larry Putnam (as Pat Waltz) | Terry Becker as Putnam's Agent | John Rodney as Commander Royce | Barbara Frederick as Noreen Carr
Director: Franklin Adreon
Writer: Art Arthur

147 :04x30 - The Saint Story

In Latin America, Mike searches a harbor for a sunken statue and discovers a homing beacon being used to guide submarines into the harbor.
Guest Stars: Victor Buono as Dr. Tank Wallace | Nestor Paiva as Tio Ramon Delgado | Pilar Del Rey as Nita Delgado | Salvador Baguez as Father Guerra (as Salvadore Baguez)
Director: Leon Benson

148 :04x31 - Impostor

An impostor posing as Mike steals diamonds from a sunken yacht but Mike is unable to provide an alibi due to the fact that he's on a top-secret mission for the government.
Guest Stars: Jean Porter as Marna Gould | Walter Reed as Case Jarrett | John Bryant as Investigator Larrabee |
Uncredited: Lloyd Bridges as Whitey Fender
Director: Leon Benson

149 :04x32 - Superman

Mike must get insulin to a diabetic whose boat has been sunk by his wife, unaware of his condition.
Guest Stars: Russ Conway as Stan Brenner | Sue Randall as Liz Brenner
Director: Leon Benson

150 :04x33 - Roustabout

In South America, Mike's assistant is trapped underwater by an overturned truck containing drums of poison that could endanger the water supply of a port city.
Guest Stars: Kenneth Tobey as Pete Butler | Anna Navarro as Maria | Rodolfo Hoyos, Jr. as Carlos (as Rodolfo Hoyos) | David Renard as Durango Lima
Director: Leon Benson
Writer: Don Archer

151 :04x34 - P.T. Boat

A rich eccentric has invented a remote control guidance device and hires Mike to test it out, but some criminals set out to steal the device.
Guest Stars: Kelton Garwood as Dr. Kendrick Kelway | Lisabeth Hush as Linda Kelway | Bert Russell as TBD | Ken Roberts (3) as TBD
Director: Leon Benson
Writer: Don Archer

152 :04x35 - Starting Signal

Someone is sabotaging a series of experiments that Mike is conducting for the Coast Guard.
Guest Stars: Robert F. Simon as Dr.Tomaso Ricou | Ross Elliott as USCG Lt. Pete Gregory | Thomas Nello as Captain Navara | Ray Parsons as Jim Parsons
Director: Leon Benson

153 :04x36 - Skipper

Mike investigates when a hydroplane rams into a Coast Guard ship during a race.
Guest Stars: Mark Andrews (1) as Johnny Cleaver | Jana Lund as Jill Bromley
Director: Dick Moder

154 :04x37 - Crime at Sea

When her father is murdered, the daughter of Mike's old Navy UDT commander asks him to investigate.
Guest Stars: Keith Andes as Todd Webster | Chris Robinson (1) as Kelsey | Sue Randall as Peg Nicholson | Harry Lauter as John Morton | Lane Bradford as Capt. Jonathan Moss | Ken Drake as George Morton | Ric Marlow as Robert Lewis Bates | Bruce Dern as John Furillo | John Rodney as Defense Attorney
Director: Leon Benson

155 :04x38 - Round Up

Mike must disarm a torpedo that's been sent into the outflow tank of a hydroelectric plant.
Guest Stars: William C. Flaherty as USCG Lt. Cozart (as William Flaherty) | Jack Nicholson as John Stark
Director: Leon Benson