What surfaces under children's play equipment

[PlugUgly1980]

I'm after ideas of what surfaces we could put down under our children's new outdoor play equipment (wooden structured climbing frame with swings). I've seen rubber mats, grass protection, bark clippings, just lawn, etc. So many options and I don't know what will work for the best. Any suggestions or things to avoid? I'd like them to be able to use it all year round, so want something durable that won't turn to mud!

No advice but I came on here to ask pretty much the same thing so hoping some folks come on that are more helpful than me!

Neighbours have a deep (about 8 inches) layer of rubber chippings like these:
www.safersurfacing.co.uk/products/playground-kits?variant=29455917744198&currency=GBP&utm_campaign=gs-2019-11-26&utm_source=google&utm_medium=smart_campaign&gclid=EAIaIQobChMIzMOk6sKZ5wIVmK3tCh2UvgQkEAYYBSABEgLQ3fD_BwE
confined by a frame of railway sleepers. They have lasted a long time (over 10 years) and don't get weeds. But in the first couple of years they did have a very fine crop of mushrooms - whether from the underlying soil or the chips themselves I don't know.

Ooh thank you! I'd not heard of rubber chippings before, they look great especially the coloured ones! I'll do some further investigation.