I think cooking, and food in general, is a great one. There's endless creativity and depth in it.

Exploring tastes from a cuisine/culture you're not that familiar with; figuring out what combinations of flavours do and don't work together; using new "tools" with stuff you're already used to eating (wok versus slow cooker versus pressure cooker versus grill versus barbecue...); experimenting with fermenting; pairing dishes with wine or cheese or whatever. The list goes on.

It's one of my favourite ways to get away from a screen and keyboard.