The invention relates to insulated submarine cables including conductive cores (3a, 3b) and insulating material (5a, 5b) surrounding the conductive cores (3a, 3b). Such an insulated cable includes a first length and a second length. The cable has a roughly constant core (3a) cross-sectional area A1 and a roughly constant insulating material (5a) thickness T1 along the first length, and a different roughly constant core (3b) cross-sectional area A3 and/or a different roughly constant insulating material (5b) thickness T2 along the second length. The cable may include one or more other lengths which join the first length and the second length to one another.