An underwater rolling seal connector assembly has releasably mateable connector units with one or more rolling seals mounted in front faces of units. The rolling seals are rotatable back and forth between a closed position sealing one or more chambers within the respective units which contain one or more contacts and an open position in which bores through the seals are open to allow contacts in one unit to pass through the seal openings and engage contact in the other unit. A shell of one connector unit has inwardly facing cam formations and each rolling seal has outwardly directed eccentric rotators configured for engagement with respective cam formations on mating and de-mating of the connector units, whereby travel of the respective rotators along the respective cam formations during mating and de-mating rotates the rolling seals into the open and closed positions, respectively.