I stirred the pot quite a bit in another thread on this topic. Best response in the entire debate was by another TUG member
"... I use a Danish product, P20 is the product name, it is sold all through Europe. I buy it on amazon or when I am traveling to Europe. You put it on ONCE a DAY, yes you read that correctly. Good for 10+ hours and it is EXTREMELY Waterproof. I go on the Tradewinds Cruising vacations frequently, I put it on once a day. I scuba dive, snorkel, and I am on boat. I don't get burnt. I eventually get a tan. But once a day is so much easier. It is more like an oil that is easily absorbed by the skin. It is not cheap, but it is cheaper than applying sunscreen 4 or 5 times a day when you are in the sun and/or swimming for a 10+ hour day.
https://www.amazon.com/Riemann-P20-Once-Hours-Protection/dp/B000RE3JM0"
Hope this is a helpful solution.
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