Stand under a tree..LOL..but seriously, having had basal cell carcinoma, I've done some research and the best plant based sunscreen is sesame oil. It absorbs 30% of UVA rays. Coconut oil absorbs 20%. I'm one of those wacky people that shuns chemicals so conventional sunscreens with all those 'other' things that would be absorbed by my skin are not an option for me.

I haven't heard of any 'natural' sunblocks. But I have had several different kinds of skin cancers, including BCCs and KAs (keratoacanthomas) and others, and I keep on getting more, and in my foolish youth I used to slather myself with coconut oil. I would not therefore rely on it or other oils for protection. Certainly the coconut oil DOES absorb the UVA rays - with a detrimental effect, in my case.

My advice would be to keep in the shade as much as possible; to wear protective clothing, including a wide-brimmed hat; to use commercial (chemical) sunscreens regardless of your dislike/distrust of them; and to stay indoors if possible during those times of the day when the sun is most 'burny' - from around 10am to around 3pm.

Some cultures cover themselves with mud, like the elephants do, to protect themselves from both the sun and insects. It doesn't have any aesthetic appeal for me, although it would provide a physical barrier!