What is your country's "coals to Newcastle"?

https://feddit.uk/post/12412136

What is your country's "coals to Newcastle"? - Feddit UK

I was talking with a friend who mentioned “taking tea to India”. It made me wonder what the equivalents are around the world. “Taking coals to Newcastle” is the UK’s.

In Poland it is „nosić drewno do lasu” (bring wood to the forest). Similar, but a bit different (pointless not just by being pointless, but by being impossible): „nie zawrócisz kijem Wisły” – 'you won't turn Vistula (our biggest river) with a stick'.
Same in Czech. Nosit dříví do lesa.