Most of them seem to perform opportunity charging (while loading/unloading), usi...

Most of them seem to perform opportunity charging (while loading/unloading), using direct rapid charging via pantograph.

See eg https://www.energymonitor.ai/sectors/transport/the-secret-to...

I have also seen designs for ferries to wirelessly charge underwater while docked.

Wireless charging can be quite efficient when the two halves comprise nesting physical features with similar tolerances to actual transformers. But I have not seen this implemented, presumably due to biofouling problems.