Stacey Haiduk, who played the role of "Katherine Hitchcock", was the leading engineer on board the submarine SeaQuest. Together with her colleague "Lucas," they were able to create the one-man submarine which was seen many times throughout the series. She left the show after the first season to star as the female lead in The Perfect Stranger (1994). She also starred in other shows such as Embraced, and The Young And The Restless.

Lieutenant "Tim O'Neill" was the communications officer on board the SeaQuest DSV. "Tim," played by Ted Raimi, specialized in foreign languages. He spoke 12 different languages fluently and often shared his knowledge with the rest of the crew. His character was one of the few which was seen in all three seasons of the show.

Ted became internationally recognized for his role as "Tim O´Neill" in SeaQuest DSV. He became even more famous after he accepted the role as "Joxer" in Xenia - Warrior Princess.

Stephanie Beacham played the role of  "Dr. Kristin Westphalen," a marine biologist as well as a medical officer on board the SeaQuest DSV. Throughout the first season of the show, she was in a relationship with the ship's captain "Nathan". Stephanie left the show after the first season and continued to work as a successful actress starring in the shows Bad Girls and Behind Bars.

Rosalind Allen, a.k.a. "Dr. Wendy Smith," became the medical officer after "Dr. Kristin Westphalen" left the crew. "Wendy" became aware of her "sixth sense" at a very young age which gave her the ability to sense thoughts and feelings in her surroundings. Rosalind Allen also left the show after one season, and began taking on smaller roles in shows like Murder One and X-Factor.

"Miguel Ortiz" was in charge of radio communications as well as piloting the SeaQuest DSV. He was also involved in several missions outside of the sub.

"Miguel Ortiz" was played by the actor Marco Sanchez. After SeaQuest, Sanchez was able to star in several different shows with the series NCIS being his most influential. In 2006, he founded a production company where he produced short films and videos.

"Dagwood" was a non-complete super soldier prototype, who, after saving lieutenant "Tim O´Neill," became a permanent member of the crew. He was a big help to the crew due to his amazing super strength. He was played by Peter DeLuise, brother of Michael DeLuise a.k.a. "Anthony Piccolo," and also gained popularity through his role in 21 Jump Street.

Lieutenant "Lonnie Henderson" was introduced as co-pilot/marine officer on board the SeaQuest DSV. Kathy Evison originally wanted to play the role of "Dr. Wendy Smith", but Rosalind Allen was given the role instead. Due to the her outstanding performance, the producers of the show decided to create the role of "Lonnie" especially for her. After numerous guest appearances in a wide variety of shows, she eventually disappeared completely from the spotlight.