Systems, equipment and components, specially designed or modified for submersible vehicles and designed to operate at depths exceeding 1 000 m, as follows: 1. Pressure housings or pressure hulls with a maximum inside chamber diameter exceeding 1,5 m; 2. Direct current propulsion motors or thrusters; 3. Umbilical cables, and connectors therefor, using optical fibre and having synthetic strength members; 4. Components manufactured from material as follows: ‘Syntactic foam’ designed for underwater use and having all of the following: a. Designed for marine depths exceeding 1 000 m; and b. A density less than 561 kg/m 3 ;