An underwater power connection system (10) has at least two separable magnetic cores (40, 50) which are operable when coupled together to form a magnetic circuit, where the at least two cores (40, 50) are provided with respective one or more windings, and said cores (40, 50) include a transverse magnetic member arrangement (60, 80) supporting magnetic limbs (70, 90), where the limbs (70, 90) are elongate and are adapted to intermesh with their lateral sides mutually abutting for providing the magnetic circuit when the system (10) is in its assembled state (210), and where the limbs (70,90) are of tapered form towards their distal ends.