The invention relates to an offshore charging station (OCS) for water vessels at least partially electrically driven comprising one or more chargers with one or more charging interfaces for wired/wireless static/dynamic charging/discharging and supported by various supporting constructions. The OCS may further comprise charging interface mounts, marine engineering constructions, facilities, operational security control elements, thermal management systems, marine attachments, payment terminals. The OCS may be part of a cloud-based communication system, a hydrogen powering system, a marine fuelling system, a marine rechargeable power source system comprising a rechargeable power source, a source management system, a buoyant or a nonbuoyant container, a charging interface, a mobility device, a payment terminal, a thermal management system, a power source. The OCS and the marine rechargeable power source may provide data transmissions and may be provided in a modular system. An offshore swapping method using the marine rechargeable power source is proposed.