Measuring over 572 feet long, 42 feet wide and 62 feet tall, the "Seaview" was an extremely large vessel. It was estimated to weight 16,500 tons and could carry a crew of between 90 to 125 enlisted personnel and civilian science staff and technicians. Power for the "Seaview" was provided by a nuclear reactor and propelled by two pump-jets. Commonly used in torpedoes, pump jets fire a jet of water to propel the vessel along. These gave the "Seaview" a top speed of over 40 knots.
Reflecting the Cold War period in which the series was created, the "Seaview" was equipped with several different types of weapons. In addition to a submarine's standard ordnance of torpedoes, the "Seaview" had 16 vertically launched nuclear missiles, one of which was used to blow the burning Van Allen belt away from Earth in the original movie version of the show. In addition, the "Seaview" was equipped with a bow laser and could electrify its own hull.
"Seaview" also carried several smaller vessels that could be deployed for more specialized work. This included a two-man wet mini-submarine, meaning a vehicle whose interior was flooded, and a two man-diving bell. The most significant vehicle the "Seaview" carried, however, was introduced in season 2. The Flying Sub or "FS-1" was a small submarine that was also capable of atmospheric flight. Much like the mini-sub, several versions of this vessel were destroyed over the course of the show.
The "Seaview" was stated as being one of a group of three submarines employed by the organization NIMR, but, ironically, was the only one of them to survive. Both the "Angler," almost identical to the "Seaview" and the "Neptune," a variant on the design, were destroyed over the course of the show. In addition, an attack variant, the "Polidor," was also introduced and destroyed.