Water polo is brutal, I saw photos of competitors coming out of the water and it looked like their legs were attacked by piranhas

Polo is the most reactionary (in Europe at least) with other equestrian events closely behind.

I’d say football (soccer for seppos) is the least reactionary, all it takes is:

• almost any space (a field ideally, but an road or alley or a yard etc is fine),
• a ball, (including a makeshift one made from plastic bags and twine),
• some goal makers (a T-shirt, rock, tree, painted bit of wall etc)
• and a mate

and you’re playing.